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  Subjects -> CHEMISTRY (Total: 931 journals)
    - ANALYTICAL CHEMISTRY (58 journals)
    - CHEMISTRY (663 journals)
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CHEMISTRY (663 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 15)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Applied Polymer Materials     Hybrid Journal  
ACS Catalysis     Hybrid Journal   (Followers: 55)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Macro Letters     Hybrid Journal   (Followers: 29)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 46)
ACS Nano     Hybrid Journal   (Followers: 378)
ACS Photonics     Hybrid Journal   (Followers: 15)
ACS Symposium Series     Full-text available via subscription   (Followers: 1)
ACS Synthetic Biology     Hybrid Journal   (Followers: 25)
Acta Chemica Iasi     Open Access   (Followers: 6)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 65)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 88)
Advances in Chemistry     Open Access   (Followers: 29)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Environmental Chemistry     Open Access   (Followers: 8)
Advances in Enzyme Research     Open Access   (Followers: 11)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 29)
Advances in Nanoparticles     Open Access   (Followers: 19)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 49)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 13)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 8)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 35)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 14)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 191)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 289)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 26)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 5)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 403)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 7)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 25)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 184)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 91)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 73)
Catalysis for Sustainable Energy     Open Access   (Followers: 10)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 10)
Catalysis Science and Technology     Hybrid Journal   (Followers: 10)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 14)
Cellulose     Hybrid Journal   (Followers: 14)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 2)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 23)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 76)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Letters : X     Open Access   (Followers: 2)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 23)
Chemical Reviews     Hybrid Journal   (Followers: 233)
Chemical Science     Open Access   (Followers: 33)
Chemical Technology     Open Access   (Followers: 49)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 191)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 17)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 22)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 46)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 284)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 12)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Hybrid Journal   (Followers: 10)
Cogent Chemistry     Open Access   (Followers: 2)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 8)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 13)
Computational Chemistry     Open Access   (Followers: 3)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 6)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 10)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Applied Spectroscopy
Journal Prestige (SJR): 0.489
Citation Impact (citeScore): 2
Number of Followers: 26  
  Full-text available via subscription Subscription journal
ISSN (Print) 0003-7028 - ISSN (Online) 1943-3530
Published by Sage Publications Homepage  [1087 journals]
  • Advertising and Front Matter
    • Pages: 1237 - 1254
      Abstract: Applied Spectroscopy, Volume 73, Issue 11, Page 1237-1254, November 2019.

      Citation: Applied Spectroscopy
      PubDate: 2019-11-06T11:02:47Z
      DOI: 10.1177/0003702819888394
  • Effects of Ambient Temperature on Laser-Induced Plasma in Bulk Water
    • Authors: Nan Li, Jinjia Guo, Lin Zhu, Yuan Lu, Ye Tian, Ronger Zheng
      Pages: 1277 - 1283
      Abstract: Applied Spectroscopy, Volume 73, Issue 11, Page 1277-1283, November 2019.
      Laser-induced breakdown spectroscopy (LIBS) has been successfully applied to ocean exploration, but the changes in marine environmental factors could have an important impact on the LIBS signals. The aim of the research is to investigate the ambient water temperature effects on laser-induced plasma in bulk water. Both the spectroscopic and fast imaging techniques are used to observe the plasma emission with the temperatures in the range of 5–60 ℃. It is shown that as the ambient temperature increases, an obviously increasing trend of emission intensity is observed, both for the atomic and ionic lines of Ca. Higher plasma temperature and electron density can be obtained at higher ambient temperature. The image results demonstrate that hotter and larger plasmas can be produced in water with the increase of ambient temperature. In addition, it is found that the changes of plasma emission and morphologies could be related to the changes of physical property parameters of water such as thermal expansivity and viscosity with ambient temperature. The results suggest that the ambient temperature has great influences on laser-induced plasma, which needs to be taken into account in underwater LIBS measurement, especially on-site marine applications.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-06T11:02:55Z
      DOI: 10.1177/0003702819856353
  • Cyclometalated Iridium Complex as Off–On–Off Reversible
           Photoluminescence Probe for Redox Cycle [math]/H2O2 in Living Cells
    • Authors: Hetong Qi, Xiaojia Zhao, Yuhai Tang, Manping Qian, Hongfang Gao, Honglan Qi
      Pages: 1292 - 1298
      Abstract: Applied Spectroscopy, Volume 73, Issue 11, Page 1292-1298, November 2019.
      The development of new methods for the detection of redox cycle is important for biological and clinical diagnoses. Here, a new cyclometalated iridium complex, (4-(2-pyridyl) benzaldehyde)2Ir (5-chloro-1,10-phenanthroline) ([(4-pba)2Ir(5-Cl-phen)]PF6, probe 1), has been synthesized and applied to rapid, sensitive, and reversible detection and imaging of redox cycle [math]/H2O2 in living cells. The probe 1 is synthesized by using 4-(2-pyridyl) benzaldehyde as main ligand and 5-chloro-1,10-phenanthroline as ancillary ligand. Probe 1 exhibited “off–on–off” photoluminescence (PL) signal change in response to [math] and H2O2 in aqueous solution within 1 min. The change of PL intensity is proportional to [math] concentration from 40 μM to 300 μM and to H2O2 concentration from 40 μM to 260 μM. The detection limit is 10 μM for [math] and 20 μM for H2O2. Additionally, probe 1 was applied to detect [math] in food samples with satisfactory results. More importantly, PL imaging of HeLa cells indicates that probe 1 is able to image redox cycle [math]/H2O2 in living cells.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-06T11:02:41Z
      DOI: 10.1177/0003702819861573
  • In Situ Monitoring of Heterogeneous Hydrosilylation Reactions Using
           Infrared and Raman Spectroscopy: Normalization Using Phase-Specific
           Internal Standards
    • Authors: Xiaoyun Chen, Yang Cheng, Masashi Matsuba, Xianghuai Wang, Shuangbing Han, Mowbray Jordan, Qing Zhu
      Pages: 1299 - 1307
      Abstract: Applied Spectroscopy, Volume 73, Issue 11, Page 1299-1307, November 2019.
      Heterogeneous reaction systems are prevalent in the chemical industry. In situ monitoring of heterogeneous reaction systems by vibrational spectroscopy techniques offers real-time composition and conversion information without sampling and with minimal perturbation. The multiphase nature introduces new challenges which are not typically encountered in the monitoring of homogeneous systems. We investigated the kinetics of the Pt catalyzed hydrosilylation reactions between allyl polyether and SiH containing silicone using both infrared (IR) and Raman spectroscopy. The reaction mixture remains biphasic for the majority of the reaction time due to the low miscibility of polyether and silicone. The results demonstrated that by normalization with appropriate internal standards (phase-specific normalization), more accurate quantitation of the SiH and allyl functional groups can be achieved based on in situ Raman results than that based on in situ attenuated total reflection Fourier transform infrared (ATR FT-IR) results. This is believed to be due to the wavelength-dependent penetration depth of the ATR mode. Raman results were obtained using two immersion optics with different focal lengths. The advantages and disadvantages of these two immersion optics are clearly illustrated in this study.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-06T11:02:51Z
      DOI: 10.1177/0003702819858916
  • Transmission Raman Spectroscopic Quantification of Active Pharmaceutical
           Ingredient in Coated Tablets of Hot-Melt Extruded Amorphous Solid
    • Authors: Yemin Liu, Jayanth Doddi, Yanbing Zheng, Vivien Ho, Maurice Pheil, Yi Shi
      Abstract: Applied Spectroscopy, Ahead of Print.
      Transmission Raman spectroscopy is an emerging technique, capable of quantitative analysis of drug products nondestructively using a multivariate data analysis approach. We developed and validated a chemometric method to quantify the active pharmaceutical ingredient in coated tablets of hot-melt extruded amorphous solid dispersion. A partial least squares regression (PLSR) model was developed and validated based on transmission Raman spectra data collected from coated tablet samples with variations in the content of active pharmaceutical ingredient, excipients, water content, a key oxidative degradant, milled extrudate particle size distribution, and tablet hardness. The method was proven to be accurate, linear, specific, and robust. Our work demonstrates that transmission Raman spectroscopy (TRS) is a viable, cost-effective, secondary method to high-performance liquid chromatography (HPLC) for quantitation of active pharmaceutical ingredient (API) in coated tablets of hot-melt extruded amorphous solid dispersion.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-13T10:20:32Z
      DOI: 10.1177/0003702819884994
  • Isotope Identification Mechanisms Enabled by Swept-Wavelength Raman
    • Authors: Calvin Zulick, Nagapratima Kunapareddy, Jacob Grun
      Abstract: Applied Spectroscopy, Ahead of Print.
      Swept-wavelength Raman signatures have been measured for isotopic variants of polyethylene, acetic acid, and potassium sulfates. The swept-wavelength measurements produce two-dimensional Raman signatures which enable identification techniques based on changes in Raman peak amplitudes as a function of wavelength. In addition to the typical Raman peak energy shifts, which results from the change in isotope mass, three wavelength dependent mechanisms for isotope identification have been identified. Changes in the shape of the Raman signal, the presence and absence of Raman peaks over specific wavelength ranges, and changes in absorption of the Raman signal were observed as a result of isotopic substitution. These features provide additional specificity in the isotopic Raman signatures which suggests swept-wavelength Raman signatures will facilitate the identification of isotopes in complex and dirty mixtures. Measurements in the visible range suggest that the identification mechanisms are primarily evident in the ultraviolet, or resonance Raman, region.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-11T03:25:30Z
      DOI: 10.1177/0003702819878232
  • Defocused Spatially Offset Raman Spectroscopy in Media of Different
           Optical Properties for Biomedical Applications Using a Commercial
           Spatially Offset Raman Spectroscopy Device
    • Authors: Martha Z. Vardaki, Dana V. Devine, Katherine Serrano, Nikolaos Simantiris, Michael W. Blades, James M. Piret, Robin F. B. Turner
      Abstract: Applied Spectroscopy, Ahead of Print.
      In this study, we show how defocused spatially offset Raman spectroscopy (SORS) can be employed to recover chemical information from media of biomedical significance within sealed plastic transfusion and culture bags using a commercial SORS instrument. We demonstrate a simple approach to recover subsurface spectral information through a transparent barrier by optimizing the spatial offset of the defocused beam. The efficiency of the measurements is assessed in terms of the SORS ratio and signal-to-noise ratio (S/N) through a simple manual approach and an ordinary least squares model. By comparing the results for three different biological samples (red blood cell concentrate, pooled red cell supernatant and a suspension of Jurkat cells), we show that there is an optimum value of the offset parameter which yields the maximum S/N depending on the barrier material and optical properties of the ensemble contents. The approach was developed in the context of biomedical applications but is generally applicable to any three-layer system consisting of turbid content between transparent thin plastic barriers (i.e., front and back bag surfaces), particularly where the analyte of interest is dilute or not a strong scatterer.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-08T04:49:54Z
      DOI: 10.1177/0003702819884625
  • Measurement and Correction Model for Temperature Dependence of an
           Acousto-Optic Tunable Filter (AOTF) Infrared Spectrometer for Lunar
           Surface Detection
    • Authors: Zhiping He, Jinning Li, Chunlai Li, Rui Xu
      Abstract: Applied Spectroscopy, Ahead of Print.
      The photoelectric response characteristics of an infrared spectrometer based on an acousto-optic tunable filter (AOTF) are greatly affected by the temperature change of the radio frequency power amplifier and shortwave infrared detector. If calibration is not conducted, that will affect the quantitative level of the data. This paper puts forward a measurement and correction method for the temperature characteristics of an AOTF infrared spectrometer which is used in lunar surface detection and sets up a temperature characteristics correction model. This model was applied to an AOTF infrared spectrometer mounted on China’s unmanned lunar rover. Laboratory tests show that the temperature causes an instrument variation of ∼20% when the temperature is between −20 ℃ and + 55 ℃, but this model reduces this variation to 
      Citation: Applied Spectroscopy
      PubDate: 2019-11-08T04:49:08Z
      DOI: 10.1177/0003702819881786
  • High-Frequency Raman Analysis in Biological Tissues Using Dual-Wavelength
           Excitation Raman Spectroscopy
    • Authors: Wencai He, Bolan Li, Shan Yang
      Abstract: Applied Spectroscopy, Ahead of Print.
      A dual-wavelength excitation Raman probe with laser inputs at 866 nm or 1064 nm is customized and integrated into a compact Raman spectrometer that is based on an InGaAs detector. Under 1064 nm illumination, the spectrometer detects fingerprint Raman signals below 2000 cm–1. While under 866 nm illumination, the spectral range is extended to cover high-frequency region (2400–4000 cm–1) that includes major C–H and O–H Raman vibrations. We demonstrate that the dual excitation InGaAs Raman is beneficial in detecting high-frequency Raman signals, especially water contents in high-fluorescent biological samples such as human dental tissues, grape skin, and plum skin due to the suppressed fluorescence interference.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-07T10:36:34Z
      DOI: 10.1177/0003702819881762
  • Laser-Induced Breakdown Spectroscopy and Principal Component Analysis for
           the Classification of Spectra from Gold-Bearing Ores
    • Authors: Daniel Diaz, Alejandro Molina, David W. Hahn
      Abstract: Applied Spectroscopy, Ahead of Print.
      Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) were applied to the classification of LIBS spectra from gold ores prepared as pressed pellets from pulverized bulk samples. For each sample, 5000 single-shot LIBS spectra were obtained. Although the gold concentrations in the samples were as high as 7.7 µg/g, Au emission lines were not observed in most single-shot LIBS spectra, rendering the application of the usual ensemble-averaging approach for spectral processing to be infeasible. Instead, a PCA approach was utilized to analyze the collection of single-shot LIBS spectra. Two spectral ranges of 21 nm and 0.15 nm wide were considered, and LIBS variables (i.e., wavelengths) reduced to no more than three principal components. Single-shot spectra containing Au emission lines (positive spectra) were discriminated by PCA from those without the spectral feature (negative spectra) in a spectral range of less than 1 nm wide around the Au(I) 267.59 nm emission line. Assuming a discrete gold distribution at very low concentration, LIBS sampling of gold particles seemed unlikely; therefore, positive spectra were considered as data outliers. Detection of data outliers was possible using two PCA statistical parameters, i.e., sample residual and Mahalanobis distance. Results from such a classification were compared with a standard database created with positive spectra identified with a filtering algorithm that rejected spectra with an Au intensity below the smallest detectable analytical LIBS signal (i.e., below the LIBS limit of detection). The PCA approach successfully identified 100% of the data outliers when compared with the standard database. False identifications in the multivariate approach were attributed to variations in shot-to-shot intensity and the presence of interfering emission lines.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-07T10:35:49Z
      DOI: 10.1177/0003702819881444
  • Application of Doehlert Matrix for an Optimized Preparation of a
           Surface-Enhanced Raman Spectroscopy (SERS) Substrate Based on Silicon
           Nanowires for Ultrasensitive Detection of Rhodamine 6G
    • Authors: Awatef Ouhibi, Maroua Saadaoui, Nathalie Lorrain, Mohammed Guendouz, Noureddine Raouafi, Adel Moadhen
      Abstract: Applied Spectroscopy, Ahead of Print.
      In this work, we combined a hierarchical nano-array effect of silicon nanowires (SiNWs) with a metallic surface of silver nanoparticles (AgNPs) to design a surface-enhanced Raman spectroscopy (SERS) scattering substrate for sensitive detection of Rhodamine 6G (R6G) which is a typical dye for fluorescence probes. The SiNWs were prepared by Metal-Assisted Chemical Etching (MACE) of n-Si (100) wafers. The Doehlert design methodology was used for planning the experiment and analyzing the experimental results. Thanks to this methodology, the R6G SERS response has been optimized by studying the effects of the silver nitrate concentration, silver nitrate and R6G immersion times and their interactions. The immersion time in R6G solution stands out as the most of influential factor on the SERS response.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-07T10:31:00Z
      DOI: 10.1177/0003702819881222
  • Clarifying Glass Luminescence at Near-Infrared Excitation
    • Authors: Marisia A. Fikiet, David Tuschel, Vladimir V. Ermolenkov, Igor K. Lednev
      Abstract: Applied Spectroscopy, Ahead of Print.
      Glass is a unique material that is often encountered in chemical and biological studies as a convenient sample holder (vial or microscope slide in particular). If the sample is probed with light in fluorescence and Raman spectroscopic experiments, the contribution from glass is often present and can obscure the spectra from the analyte of interest. It is important to understand the nature of glass photoemission properties to control this potential interference. The Raman spectrum of glass is dominated by peaks around 500 and 1000 cm–1 at the excitation with UV and visible light. A strong broad emission band centered at 880 nm appears when glass is irradiated with near-infrared light, a popular 785 nm laser light in particular. We proved experimentally in this study that this broad band is due to glass photoluminescence and not Raman scattering. In addition, three narrow components were found to contribute to this band, which have different excitation profiles indicating that they originate from three different species or the same species experiencing three different types of local environments. It has been hypothesized that these peaks could be due to the presence of rare earth impurities in the glass. Further study is necessary to identify these luminescent centers.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-04T11:11:22Z
      DOI: 10.1177/0003702819879109
  • Evaluating Low-Cost Optical Spectrometers for the Detection of Simulated
           Substandard and Falsified Medicines
    • Authors: Wenbo Wang, Matthew D. Keller, Ted Baughman, Benjamin K. Wilson
      Abstract: Applied Spectroscopy, Ahead of Print.
      Distribution of substandard and falsified (SF) medicines is on the rise, and its impact on public health, particularly in low-resource countries, is becoming increasingly significant. Portable, nondestructive screening devices can support regulatory authorities in their defense against the spread of SF medicines. Vibrational spectroscopy is an ideal candidate due to its sampling ease and speed. In this work, five portable, among which four are considered low-cost, spectroscopic devices based on near-infrared (NIR), Raman, and mid-infrared (MIR) were evaluated to quantify active pharmaceutical ingredients (APIs) and formulation accuracy within simulated authentic, falsified, and substandard medicines. Binary sample mixtures containing a typical API in antimalarial, antiretroviral, or anti-tuberculosis medicines were assessed. In both univariate and multivariate analyses, the API quantification performance of the digital light processing (DLP) NIR spectrometer and a handheld Raman device consistently matched or exceeded that of the other NIR spectrometers and a scientific grade MIR spectrometer. In the formulation accuracy tests, data from all devices, other than the silicon photodiode array NIR spectrometer, were able to create regression models with less than 6% error. From this exploratory study, we conclude that certain portable NIR devices hold significant promise as cost-effective screening tools for falsified and potentially substandard medicines, and they warrant further investigation and development.
      Citation: Applied Spectroscopy
      PubDate: 2019-11-04T11:09:49Z
      DOI: 10.1177/0003702819877422
  • High-Precision Continuous-Wave Terahertz Spectroscopy Based on a
           Photomixing Technique for Identifying Pearls
    • Authors: Chihoon Kim, Taeksoo Ji
      Abstract: Applied Spectroscopy, Ahead of Print.
      We present the accurate terahertz spectra of between imitation and cultured pearls using continuous-wave terahertz (CW-THz) spectroscopy. Using Fourier transform infrared (FT-IR) spectroscopy and optical coherence tomography (OCT) measurements, cultured pearls can be distinguished from imitation pearls by observing distinct absorption peaks and discriminative boundaries. The THz absorption spectra up to 0.3 THz obtained from CW-THz spectroscopy show several absorption peaks at specific frequencies with the cultured pearls but no peaks with the imitation pearls, which results from the existence of the nacre polymorph of cultured pearls. Hence, it is expected that the CW-THz system proposed herein will be applicable to fast, nondestructive spectrum analysis including pearl identification.
      Citation: Applied Spectroscopy
      PubDate: 2019-10-30T02:45:03Z
      DOI: 10.1177/0003702819877261
  • Monitoring the Kinetics of the Cellular Uptake of a Metal Carbonyl
           Conjugated with a Lipidic Moiety in Living Cells Using Synchrotron
           Infrared Spectromicroscopy
    • Authors: Sylvain Clède, Christophe Sandt, Paul Dumas, Clotilde Policar
      Abstract: Applied Spectroscopy, Ahead of Print.
      Presented here is the exploitation of synchrotron infrared spectromicroscopy to evaluate the feasibility of monitoring the cellular uptake of rhenium-tris-carbonyl-tagged (Re(CO)3) lipophilic chains in living cells. To this aim, an in-house thermostated microfluidic device was used to limit water absorption while keeping cells alive. Indeed, cells showed a high survival rate in the microfluidic device over the course of the experiment, proving the short-term biocompatibility of the device. We recorded spectra of single, living, fully hydrated breast cancer MDA-MB231 cells and could follow the penetration of the rhenium complexes for up to 2 h. Despite the strong variations observed in the uptake kinetics between individual cells, the Re(CO)3 complex was traced inside the cells at low concentration and shown to enter them on the hour time scale by active transport.
      Citation: Applied Spectroscopy
      PubDate: 2019-10-16T12:01:31Z
      DOI: 10.1177/0003702819877260
  • Remote Raman Detection of Chemicals from 1752 m During Afternoon
    • Authors: Anupam K. Misra, Tayro E. Acosta-Maeda, John N. Porter, Miles J. Egan, Macey W. Sandford, Tamra Oyama, Jie Zhou
      Abstract: Applied Spectroscopy, Ahead of Print.
      The detection and identification of materials from a distance is highly desirable for applications where accessibility is limited or there are safety concerns. Raman spectroscopy can be performed remotely and provides a very high level of confidence in detection of chemicals through vibrational modes. However, the remote Raman detection of chemicals is challenging because of the very weak nature of Raman signals. Using a remote Raman system, we performed fast remote detection of various solid and liquid chemicals from 1752 m during afternoon hours on a sunny day in Hawaii. Remote Raman systems with kilometer target range could be useful for chemical detection of volcanic gases, methane clathrate icebergs or fire ice, toxic gas clouds and toxic waste, explosives, and hazardous chemicals. With this successful test, we demonstrate the feasibility of developing future mid-size remote Raman systems suitable for long range chemical detection using helicopters and light airplanes.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-13T03:13:56Z
      DOI: 10.1177/0003702819875437
  • Simulation of Vacuum Ultraviolet Absorption Spectra: Paraffin,
           Isoparaffin, Olefin, Naphthene, and Aromatic Hydrocarbon Class Compounds
    • Authors: James X. Mao, Phillip Walsh, Peter Kroll, Kevin A. Schug
      Abstract: Applied Spectroscopy, Ahead of Print.
      The advent of a new vacuum ultraviolet (VUV) spectroscopic absorption detector for gas chromatography has enabled applications in many areas. Theoretical simulations of VUV spectra using computational chemistry can aid the new technique in situations where experimental spectra are unavailable. In this study, VUV spectral simulations of paraffin, isoparaffin, olefin, naphthene, and aromatic (PIONA) compounds using time-dependent density functional theory (TDDFT) methods were investigated. Important factors for the simulations, such as functionals/basis sets and formalism of oscillator strength calculations, were examined and parameters for future PIONA compound simulations were obtained by fitting computational results to experimental spectra. The simulations produced satisfactory correlations between experimental observations and theoretical calculations, and enabled potential analysis applications for complex higher distillate fuels, such as diesel fuel. Further improvement of the methods was proposed.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-13T03:11:37Z
      DOI: 10.1177/0003702819875132
  • Raman Spectroscopic and Chemometric Investigation of Lipid–Protein Ratio
           Contents of Soybean Mutants
    • Authors: Gulce Ogruc Ildiz, Ozge Celik, Cimen Atak, Ayberk Yilmaz, Hayrunnisa Nur Kabuk, Ersin Kaygisiz, Alp Ayan, Sinan Meric, Rui Fausto
      Abstract: Applied Spectroscopy, Ahead of Print.
      Seeds belonging to fourth generation mutants (M4) of Ataem-7 cultivar (A7) variety and S04-05 (S) breeding line salt-tolerant soybeans were investigated by Raman spectroscopy, complemented by chemometrics methods, in order to evaluate changes induced by mutations in the relative lipid–protein contents, and to find fast, efficient strategies for discrimination of the mutants and the control groups based on their Raman spectra. It was concluded that gamma irradiation caused an increase in the lipid to protein ratio of the studied Ataem-7 variety mutants, while it led to a decrease of this ratio in the investigated S04-05 breeding line mutants. These results were found to be in agreement with data obtained by reflectance spectrum analysis of the seeds in the full ultraviolet to near-infrared spectral region and suggest the possibility of developing strategies where gamma irradiation can be used as a tool to improve mutant soybean plants targeted to different applications, either enriched in proteins or in lipids. Ward's clustering and principal component analysis showed a clear discrimination between mutants and controls and, in the case of the studied S-type species, discrimination between the different mutants. The grouping scheme is also found to be in agreement with the compositional information extracted from the analysis of the lipid–protein contents of the different samples.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-13T03:09:40Z
      DOI: 10.1177/0003702819859940
  • An Open Source, Iterative Dual-Tree Wavelet Background Subtraction Method
           Extended from Automated Diffraction Pattern Analysis to Optical
    • Authors: Robert B. Chevalier, Jason R. Dwyer
      Abstract: Applied Spectroscopy, Ahead of Print.
      Background subtraction is a general problem in spectroscopy often addressed with application-specific techniques, or methods that introduce a variety of implementation barriers such as having to specify peak-free regions of the spectrum. An iterative dual-tree complex wavelet transform-based background subtraction method (DTCWT-IA) was recently developed for the analysis of ultrafast electron diffraction patterns. The method was designed to require minimal user intervention, to support streamlined analysis of many diffraction patterns with complex overlapping peaks and time-varying backgrounds, and is implemented in an open-source computer program. We examined the performance of DTCWT-IA for the analysis of spectra acquired by a range of optical spectroscopies including ultraviolet–visible spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS), and surface-enhanced Raman spectroscopy (SERS). A key benefit of the method is that the user need not specify regions of the spectrum where no peaks are expected to occur. SER spectra were used to investigate the robustness of DTCWT-IA to signal-to-noise levels in the spectrum and to user operation, specifically to two of the algorithm parameter settings: decomposition level and iteration number. The single, general DTCWT-IA implementation performs well in comparison to the different conventional approaches to background subtraction for UV–Vis, XPS, and SERS, while requiring minimal input. The method thus holds the same potential for optical spectroscopy as for ultrafast electron diffraction, namely streamlined analysis of spectra with complex distributions of peaks and varying signal levels, thus supporting real-time spectral analysis or the analysis of data acquired from different sources.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-13T03:09:00Z
      DOI: 10.1177/0003702819871330
  • Identification of a Glass Substrate to Study Cells Using Fourier Transform
           Infrared Spectroscopy: Are We Closer to Spectral Pathology'
    • Authors: Abigail V. Rutter, Jamie Crees, Helen Wright, Marko Raseta, Daniel G. van Pittius, Paul Roach, Josep Sulé-Suso
      Abstract: Applied Spectroscopy, Ahead of Print.
      The rising incidence of cancer worldwide is causing an increase in the workload in pathology departments. This, coupled with advanced analysis methodologies, supports a developing need for techniques that could identify the presence of cancer cells in cytology and tissue samples in an objective, fast, and automated way. Fourier transform infrared (FT-IR) microspectroscopy can identify cancer cells in such samples objectively. Thus, it has the potential to become another tool to help pathologists in their daily work. However, one of the main drawbacks is the use of glass substrates by pathologists. Glass absorbs IR radiation, removing important mid-IR spectral data in the fingerprint region (1800 cm−1 to 900 cm−1). In this work, we hypothesized that, using glass coverslips of differing compositions, some regions within the fingerprint area could still be analyzed. We studied three different types of cells (peripheral blood mononuclear cells, a leukemia cell line, and a lung cancer cell line) and lymph node tissue placed on four different types of glass coverslips. The data presented here show that depending of the type of glass substrate used, information within the fingerprint region down to 1350 cm−1 can be obtained. Furthermore, using principal component analysis, separation between the different cell lines was possible using both the lipid region and the fingerprint region between 1800 cm−1 and 1350 cm−1. This work represents a further step towards the application of FT-IR microspectroscopy in histopathology departments.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-13T03:05:15Z
      DOI: 10.1177/0003702819875828
  • Simple Defocused Fiber Optic Volume Probe for Subsurface Raman
           Spectroscopy in Turbid Media
    • Authors: Anders Runge Walther, Morten Østergaard Andersen, Christine Kamstrup Dam, Frederikke Karlsson, Martin Aage Barsøe Hedegaard
      Abstract: Applied Spectroscopy, Ahead of Print.
      We investigated the ability to perform deep subsurface Raman spectroscopy in turbid media using a simple fiber optic volume probe. Being able to collect Raman signals from regions deep within a biological sample provides the ability to noninvasively study underlying living tissue and tissue engineered constructs with high chemical specificity. Spatially offset Raman spectroscopy has shown great potential for obtaining subsurface Raman signals in biological samples. The applicability of the method for in vivo studies depends on the system complexity and small size probes are often desirable. Most real-time studies on human patients utilizing Raman spectroscopy have been performed with easy-to-handle miniaturized probes. Here we show both experimentally and theoretically that the sampling depth from a simple volume probe can be controlled by changing the probe to sample distance effectively suppressing Raman and fluorescence contributions from shallow sample layers while favoring the collection of signals from deeper layers. Relative spectral intensities as function of probe to sample distance were investigated for layered phantoms of poly(methyl methacrylate) and trans-stilbene and compared with theory. The volume probe was then utilized for the collection of spectra from phantoms mimicking in vivo transcutaneous measurement configurations of bone and engineered scaffold as well as from an ex vivo sample of bone and soft tissue. Together the results show that Raman fiber optic volume probes can be utilized for subsurface Raman spectroscopy in turbid media, providing a simple alternative to spatially offset Raman systems for, e.g., noninvasive monitoring and studying mineralized tissue and implanted scaffolds in vivo.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-12T08:56:11Z
      DOI: 10.1177/0003702819873933
  • An Optimizing Dynamic Spectrum Differential Extraction Method for
           Noninvasive Blood Component Analysis
    • Authors: Wei Tang, Qiang Chen, Wenjuan Yan, Guoquan He, Gang Li, Ling Lin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Dynamic spectra (DS) can greatly reduce the influence of individual differences and the measurement environment by extracting the absorbance of pulsating blood at multiple wavelengths, and it is expected to achieve noninvasive detection of blood components. Extracting high-quality DS is the prerequisite for improving detection accuracy. This paper proposed an optimizing differential extraction method in view of the deficiency of existing extraction methods. In the proposed method, the sub-dynamic spectrum (sDS) is composed by sequentially extracting the absolute differences of two sample points corresponding to the height of the half peak on the two sides of the lowest point in each period of the logarithm photoplethysmography signal. The study was based on clinical trial data from 231 volunteers. Single-trial extraction method, original differential extraction method, and optimizing differential extraction method were used to extract DS from the volunteers’ experimental data. Partial least squares regression (PLSR) and radial basis function (RBF) neural network were used for modeling. According to the effect of PLSR modeling, by extracting DS using the proposed method, the correlation coefficient of prediction set (Rp) has been improved by 17.33% and the root mean square error of prediction set has been reduced by 7.10% compared with the original differential extraction method. Compared with the single-trial extraction method, the correlation coefficient of calibration set (Rc) has increased from 0.747659 to 0.8244, with an increase of 10.26%, while the correlation coefficient of prediction set (Rp) decreased slightly by 3.22%, much lower than the increase of correction set. The result of the RBF neural network modeling also shows that the accuracy of the optimizing differential method is better than the other two methods both in calibration set and prediction set. In general, the optimizing differential extraction method improves the data utilization and credibility compared with the existing extraction methods, and the modeling effect is better than the other two methods.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-12T08:55:10Z
      DOI: 10.1177/0003702818815508
  • Quantitative Analysis of Iron and Silicon Concentrations in Iron Ore
           Concentrate Using Portable X-ray Fluorescence (XRF)
    • Authors: Shubin Zhou, Zhaoxian Yuan, Qiuming Cheng, David C. Weindorf, Zhenjie Zhang, Jie Yang, Xiaolong Zhang, Guoxiong Chen, Shuyun Xie
      Abstract: Applied Spectroscopy, Ahead of Print.
      As a technique capable of rapid, nondestructive, and multi-elemental analysis, portable X-ray fluorescence (pXRF) has applications to mineral exploration, environmental evaluation, and archaeological analysis. However, few applications have been conducted in the smelting industry especially when analyzing the metal concentration in ore concentrate samples. This research analyzed the effectiveness of using pXRF in determining the metal concentration in Fe concentrate. For this proof of concept study, Fe ore samples dominated by Fe and Si were collected from the Northeastern University Mineral Processing Laboratory (Shenyang, China) and directly analyzed using pXRF, laboratory-based XRF, and titration methods. The compactness (density) of the ore concentrate was found to have very little effect on pXRF readings. The pXRF readings for Fe and Si were comparative to laboratory-based XRF results. Based on the strong correlations between the pXRF and XRF results (Fe: R2 > 0.99, Si: R2 > 0.96), linear calibrations were adopted to improve the accuracy of pXRF readings. Linear regression equations derived from the relations between XRF results and pXRF results of 21 Fe ore concentrate samples were used to calibrate the pXRF, and then validation was performed on five additional samples. Results from this preliminary study suggest that ordinary least squares (OLS) regression improves the accuracy dramatically, especially for Fe with relative errors (REs) decreasing to 0.03%–3.27% from 4.26%–8.32%. Consequently, pXRF shows strong promise for rapid, quantitative analysis of Fe concentration in Fe ore concentrate. Based on the results obtained in this study, a larger, more comprehensive study is warranted to confirm the results obtained.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-12T08:53:22Z
      DOI: 10.1177/0003702819871627
  • Optimization of a Commercial Variable Angle Accessory for Entry Level
           Users of Electrochemical Attenuated Total Reflection Surface-Enhanced
           Infrared Absorption Spectroscopy (ATR-SEIRAS)
    • Authors: Jessica A. Sigrist, Erick S. Lins, Tyler A. Morhart, Jenni L. Briggs, Ian J. Burgess
      Abstract: Applied Spectroscopy, Ahead of Print.
      An evaluation of several experimental aspects that can optimize electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) performance using a commercially available, specular reflection accessory is provided. A comparison of different silicon single-bounce internal reflection elements (IREs) is made with emphasis on different face-angled crystal (FAC) options. Selection of optimal angle of incidence for maximizing signal and minimizing noise is shown to require consideration of the optical throughput of the accessory, reflection losses at the crystal surfaces, and polarization effects. The benefits of wire-grid polarizers and antireflective (AR) coatings on the IREs is discussed. High signal-to-noise ratios can be achieved by omitting polarizers, using an AR-coated FAC with a larger face angle, and working at angles of incidence close to the maximum throughput angle of the accessory.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-04T03:40:38Z
      DOI: 10.1177/0003702819858353
  • Optimizing the Analytical Performance of Substrate-Integrated Hollow
           Waveguides: Experiment and Simulation
    • Authors: L. Tamina Hagemann, Sonja Ehrle, Boris Mizaikoff
      Abstract: Applied Spectroscopy, Ahead of Print.
      The goal of this technical note was to compare experimentally and via simulation of eight substrate-integrated hollow waveguide (iHWG) designs, and to predict promising future iHWG structures in lieu of experiments. The iHWGs differed in their geometry (i.e., inlet funnel cross-section and inner channel cross-section), as well as in their material properties (i.e., type of metal, polish of inner channel). Experimentally, calibration functions of isobutane as a model analyte were determined, and the analytical figures of merit, i.e., signal-to-noise ratio, limit of detection, were evaluated for each iHWG. Evaluation of the amount of radiation incident at the real-world and simulated detector revealed that experiment and simulation were in excellent agreement. While material and quality of the inner channel wall did not have a significant influence on the performance, the iHWG geometry profoundly affected the performance in terms of light throughput: Increasing the inlet funnel dimensions and the inner channel cross-section benefits light throughout, and thus, the analytical signal. Based on these results, simulations of not yet fabricated iHWGs were performed and promising new iHWG structures were suggested.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-22T10:46:40Z
      DOI: 10.1177/0003702819867342
  • Improved Vancouver Raman Algorithm Based on Empirical Mode Decomposition
           for Denoising Biological Samples
    • Authors: Fabiola León-Bejarano, Martin O. Méndez, Miguel G. Ramírez-Elías, Alfonso Alba
      Abstract: Applied Spectroscopy, Ahead of Print.
      A novel method based on the Vancouver Raman Algorithm (VRA) and Empirical Mode Decomposition (EMD) for denoising Raman spectra of biological samples is presented. The VRA is one of the most used methods for denoising Raman spectroscopy and is composed of two main steps: signal filtering and polynomial fitting. However, the signal filtering step consists in a simple mean filter that could eliminate spectrum peaks with small intensities or merge relatively close spectrum peaks into one single peak. Thus, the result is often sensitive to the order of the mean filter, so the user must choose it carefully to obtain the expected result; this introduces subjectivity in the process. To overcome these disadvantages, we propose a new algorithm, namely the modified-VRA (mVRA) with the following improvements: (1) to replace the mean filter step by EMD as an adaptive parameter-free signal processing method; and (2) to automate the selection of polynomial degree. The denoising capabilities of VRA, EMD, and mVRA were compared in Raman spectra of artificial data based on Teflon material, synthetic material obtained from vitamin E and paracetamol, and biological material of human nails and mouse brain. The correlation coefficient (ρ) was used to compare the performance of the methods. For the artificial Raman spectra, the denoised signal obtained by mVRA ([math]) outperforms VRA ([math]) for moderate to high noise levels whereas mVRA outperformed EMD ([math]) for high noise levels. On the other hand, when it comes to modeling the underlying fluorescence signal of the samples (i.e., the baseline trend), the proposed method mVRA showed consistent results ([math]. For Raman spectra of synthetic material, good performance of the three methods ([math] for VRA, [math] for EMD, and [math] for mVRA) was obtained. Finally, in the biological material, mVRA and VRA showed similar results ([math] for VRA, [math] for EMD, and [math] for mVRA); however, mVRA retains valuable information corresponding to relevant Raman peaks with small amplitude. Thus, the application of EMD as a filter in the VRA method provides a good alternative for denoising biological Raman spectra, since the information of the Raman peaks is conserved and parameter tuning is not required. Simultaneously, EMD allows the baseline correction to be automated.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-14T03:25:25Z
      DOI: 10.1177/0003702819860121
  • In Situ Raman Spectroscopic Studies of Liquid Carbon Tetrachloride (CCl4)
           Under Static and Laser-Driven Shock Compression
    • Authors: Usha Rao, Shivanand Chaurasia, C. D. Sijoy, Vinayak Mishra, M. N. Deo
      Abstract: Applied Spectroscopy, Ahead of Print.
      High pressure (up to ∼2.2 GPa) Raman scattering studies were performed in carbon tetrachloride (CCl4) under static and dynamic compressions using diamond anvil cell (DAC) and laser-driven shock methods, respectively, and their results are compared. The laser-driven shock experiments were conducted in a glass-confined target geometry. The symmetric stretching mode ν1, symmetric bending mode ν2, and asymmetric bending mode ν4 blueshifts with pressure. Mode Gruneisen parameters were obtained for the above Raman modes. Time-resolved Raman spectroscopic (TRRS) studies were performed under laser-driven shock compression at different delay times. Shock velocity deduced from the intensity ratios of Raman signal scattered from unshocked and shocked regions of symmetric stretching mode is in agreement with the one obtained from one-dimensional hydrodynamic simulations.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-12T12:13:30Z
      DOI: 10.1177/0003702819856372
  • Tagged Core-Satellite Nanoassemblies: Role of Assembling Sequence on
           Surface-Enhanced Raman Scattering (SERS) Performance
    • Authors: Priyanka Dey, Kristofer J. Thurecht, Peter M. Fredericks, Idriss Blakey
      Abstract: Applied Spectroscopy, Ahead of Print.
      Plasmonic nanoassemblies with amplified optical responses are attractive as chemo/bio sensors and diagnostic tracking agents. For real-life implementation, such nanostructures require a well-designed and controlled formation for maximizing the optical amplification. Forming these nanoassemblies typically requires numerous steps; however, the importance of the sequence of the steps is typically not discussed. Thus, here we have investigated the role of the sequence of tagging (or labeling, barcoding) of such plasmonic nanoassemblies with Raman active molecules in a quest to maximize the surface-enhanced Raman scattering (SERS) enhancement that could be achieved from the nanoassemblies. We have chosen the core-satellite nanoassembly arrangement to study the role of tagging sequence because it allows us to keep structural parameters constant that would otherwise influence the SERS amplification. We demonstrate that incorporating the tag molecule at an assembly point before formation of the nanojunctions leads to more tag molecules being positioned at the core-satellite nanojunctions, thereby resulting in higher SERS signal enhancement. This will thus prove to be a useful tool in fully utilizing the nanoassembly morphology generated hot-spot and maximizing its SERS performance.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-08T08:33:55Z
      DOI: 10.1177/0003702819856666
  • Solid Parahydrogen Thickness Revisited
    • Authors: Mario E. Fajardo
      Abstract: Applied Spectroscopy, Ahead of Print.
      We report updated infrared (IR) absorption measurements on vapor-deposited cryogenic parahydrogen (pH2) solids that indicate a ≈10% systematic error in our previous approach for determining a pH2 solid's thickness (S. Tam and M.E. Fajardo. Appl. Spectrosc. 2001. 55(12): 1634-1644). We provide corrected values for the integrated absorption intensities of the Q1(0)+S0(0) and S1(0)+S0(0) bands calculated over the 4495–4520 cm−1 and 4825–4855 cm−1 regions, respectively. New polarized IR absorption spectroscopy data demonstrate the insensitivity to polarization effects of the peak intensity of the QR(0) phonon sideband near 4228 cm−1. This feature provides an even quicker way for determining the thickness of a pH2 solid than via the integrated absorptions.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-02T03:46:15Z
      DOI: 10.1177/0003702819861581
  • Analysis and Classification of Liquid Samples Using Spatial Heterodyne
           Raman Spectroscopy
    • Authors: Ardian B. Gojani, Dávid J. Palásti, Andrea Paul, Gábor Galbács, Igor B. Gornushkin
      Abstract: Applied Spectroscopy, Ahead of Print.
      Spatial heterodyne spectroscopy (SHS) is used for quantitative analysis and classification of liquid samples. SHS is a version of a Michelson interferometer with no moving parts and with diffraction gratings in place of mirrors. The instrument converts frequency-resolved information into a spatially resolved one and records it in the form of interferograms. The back-extraction of spectral information is done by the fast Fourier transform. A SHS instrument is constructed with the resolving power 5000 and spectral range 522–593 nm. Two original technical solutions are used as compared to previous SHS instruments: the use of a high-frequency diode-pumped solid-state laser for excitation of Raman spectra and a microscope-based collection system. Raman spectra are excited at 532 nm at the repetition rate 80 kHz. Raman shifts between 330 cm−1 and 1600 cm−1 are measured. A new application of SHS is demonstrated: for the first time, it is used for quantitative Raman analysis to determine concentrations of cyclohexane in isopropanol and glycerol in water. Two calibration strategies are employed: univariate based on the construction of a calibration plot and multivariate based on partial least squares regression. The detection limits for both cyclohexane in isopropanol and glycerol in water are at a 0.5 mass% level. In addition to the Raman–SHS chemical analysis, classification of industrial oils (biodiesel, poly(1-decene), gasoline, heavy oil IFO380, polybutenes, and lubricant) is performed using the Raman–fluorescence spectra of the oils and principal component analysis. The oils are easily discriminated showing distinct non-overlapping patterns in the principal component space.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-01T10:06:11Z
      DOI: 10.1177/0003702819863847
  • A Review of Chinese Raman Spectroscopy Research Over the Past Twenty Years
    • Authors: Jie Wang, Kaiyuan Liu, Shangzhong Jin, Li Jiang, Pei Liang
      Abstract: Applied Spectroscopy, Ahead of Print.

      Citation: Applied Spectroscopy
      PubDate: 2019-03-21T04:08:52Z
      DOI: 10.1177/0003702819828360
  • Multi-Analytical Study of Copper-Based Historic Pigments and their
           Alteration Products
    • Authors: Marcie B. Wiggins, Emma Heath, Karl S. Booksh, Jocelyn Alcántara-García
      First page: 1255
      Abstract: Applied Spectroscopy, Ahead of Print.
      Copper-containing materials such as verdigris are commonly found in historic and artistic works of art, often at advanced states of decay. Applied on paper as inks and watercolors, many of which needed a binder such as gum arabic, the intrinsic instability of this pigment was known since the medieval period. The decay of verdigris (a mixture of copper acetates) as a pigment, as watercolor, and as a dye, was studied using a combination of vibrational (Fourier transform infrared) and X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) instrumental techniques. Changes in the copper oxidative states and the formation of copper oxide were monitored during accelerated degradation as powdered solids and applied on mockup samples (with and without binder). Accelerated aging of both commercially available and synthesized verdigris pigments showed the presence of an intermediate species, Cu(CH3COO)2•3Cu(OH)2•2H2O, which points to the beginning of the decay processes, that culminates in the formation of Cu(II) oxide. However, the presence of gum arabic seems to delay deterioration, by temporarily reducing Cu(II) to Cu(I), even when the final product includes Cu(II). This novel application of XPS and supporting techniques has significant implications in art conservation, as the identified behavior helps explain the better preservation state of some works of art.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-08T02:17:20Z
      DOI: 10.1177/0003702819856606
  • Shifted Excitation Raman Difference Spectroscopy with Charge-Shifting
           Charge-Coupled Device (CCD) Lock-In Detection
    • Authors: Kay Sowoidnich, Michael Towrie, Martin Maiwald, Bernd Sumpf, Pavel Matousek
      First page: 1265
      Abstract: Applied Spectroscopy, Ahead of Print.
      Shifted excitation Raman difference spectroscopy (SERDS) can provide effective, chemically specific information on fluorescent samples. However, the restricted ability for fast alternating detection (usually 
      Citation: Applied Spectroscopy
      PubDate: 2019-08-12T12:12:42Z
      DOI: 10.1177/0003702819859352
  • Rapid and Sensitive Analysis of Trace Leads in Medicinal Herbs Using
           Laser-Induced Breakdown Spectroscopy–Laser-Induced Fluorescence
    • Authors: Yinhua Jiang, Juan Kang, Yarui Wang, Yuqi Chen, Runhua Li
      First page: 1284
      Abstract: Applied Spectroscopy, Ahead of Print.
      Toxic metals in medicinal herbs are potentially harmful for people taking herbal medicines. In this work, laser-induced breakdown spectroscopy–laser-induced fluorescence (LIBS-LIF) spectroscopy was first applied to carry out rapid and sensitive trace lead analysis in medicinal herb samples. To overcome the problem of diversity on the sample size, shape, and density for different samples, original samples were pulverized to powder and then pressed into pellets for spectral analysis. A series of standard samples were self-made for building a calibration curve. As an exemplary study, lead in Rheum officinale was analyzed with LIBS-LIF spectroscopy with significantly improved analytical sensitivity. The R2 of the build linear calibration curve was 0.996 and the detection limit of lead in R. officinale was determined to be 0.13 ppm. The enhancement factor on the signal-to-background ratio was>100 under low lead concentrations if compared with LIBS analysis. The lead concentrations in several original R. officinale samples were quantitatively determined. This work demonstrated that LIBS-LIF can be successfully applied to carry out rapid, sensitive, and quantitative trace lead analysis for medicinal herbs.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-08T02:16:40Z
      DOI: 10.1177/0003702819857740
  • Calibrated Optical Markers to Study Thermal Degradation in Edible Oils
           Using Raman and Optical Transmission Spectroscopy
    • Authors: Ho-Ying Lam, Sandip Ghosh, Surojit Chattopadhyay
      First page: 1308
      Abstract: Applied Spectroscopy, Ahead of Print.
      An “all optical” methodology, including Raman and optical transmission spectroscopy, is presented to study the thermal degradation in edible oils. Oils rich in monounsaturated (MU), polyunsaturated (PU), and saturated (S) fatty acids (FA) were heated above and below their smoke point (∼230 ℃). While the intensity (I) of the identified saturated (C–C, 1440 cm−1) FA Raman marker did not change appreciably, the identified unsaturated (C=C, 1265 cm−1) FA marker decreased in these oils when heated above the smoke point. A Raman parameter, I1265/I1440, designating thermal degradation, is proposed that was found to decrease consistently for the PUFA-rich and MUFA-rich oils when heated above the smoke point, while the SFA-rich oil did not degrade at all over the whole temperature range. An optical transmission marker at 2140 nm was identified that decreased consistently with increased thermal stressing. These markers can be calibrated with the variations in the quantitative iodine value, an industrial benchmark for the degree of unsaturation, for thermally stressed oils.
      Citation: Applied Spectroscopy
      PubDate: 2019-07-30T12:12:27Z
      DOI: 10.1177/0003702819856369
  • Rheo-Optical Near-Infrared (NIR) Characterization of
           Hydroxyl-Functionalized Polypropylene (PPOH)-Mesoporous Silica
           Nanocomposites Using Two-Trace Two-Dimensional (2T2D) Correlation Analysis
    • Authors: Ryota Watanabe, Hideaki Hagihara, Hiroaki Sato, Junji Mizukado, Hideyuki Shinzawa
      First page: 1317
      Abstract: Applied Spectroscopy, Ahead of Print.
      A rheo-optical characterization technique based on the combination of near-infrared (NIR) spectroscopy and mechanical analysis was applied to the nanocomposite consisting of hydroxyl-functionalized polypropylene (PPOH) and mesoporous silica (MPS) to probe the deformation behavior. Substantial levels of spectral changes of NIR spectral features were captured when the polymer samples underwent tensile deformation. Sets of spectra were subjected to projection treatment to remove the effect of baseline fluctuations and thickness change inevitably caused by the tensile deformation of the sample. Then, two-trace two-dimensional (2T2D) correlation spectroscopy was applied to the pretreated spectra to elucidate spectroscopic signature associated with the difference between the initial and deformed samples. An asynchronous correlation peak appears between the bands at 1720 and 1700 nm respectively reflecting the contributions of predominantly amorphous and crystalline component of the PPOH, indicating the predominant variation of amorphous structure followed by that of crystalline structure. In addition, the predominant spectral change related to the amorphous band becomes even more acute by including the MPS with large pores. It is hence likely that the larger pore size of the MPS confines the more amorphous structure, which, in turn, causes simultaneous reorientation of the polymer chains in the amorphous region during the elastic deformation. Consequently, the incorporation of the MPS selectively restricts the deformation of the amorphous structure which eventually provides the obvious increase in the mechanical property of the PPOH polymer.
      Citation: Applied Spectroscopy
      PubDate: 2019-07-25T09:17:55Z
      DOI: 10.1177/0003702819861564
  • Trace Gas Detection System Based on All-Optical Quartz-Enhanced
           Photoacoustic Spectroscopy
    • Authors: Cheng Lin, Yu Liao, Fei Fang
      First page: 1327
      Abstract: Applied Spectroscopy, Ahead of Print.
      An all-optical quartz-enhanced photoacoustic spectroscopy system (QEPAS) with quadrature point stabilization for trace gas detection was reported. The extrinsic interferometry-based optical fiber Fabry–Perot sensor with quadrature point self-stabilization for detection of quartz prong vibration was used to replace the conventional one. The optimal coefficient of the modulation depth was ∼2.2 theoretically and experimentally, corresponding to the modulation depth of ∼0.1795 cm−1 at an acetylene (C2H2) absorption line of 6534.36 cm−1. Furthermore, the enhancement of QEPAS signal was obtained by using different microresonators. The minimum detectable limit of ∼580 parts per billion by volume (ppbv) was obtained. A normalized noise equivalent absorption coefficient for C2H2 of 2.95 × 10−7 cm−1·W·Hz–1/2 was obtained. The detection sensitivity was enhanced by a factor of ∼2.1 in comparison to the conventional QEPAS system. The linear correlation coefficient of the QEPAS signal response to the C2H2 concentration was 0.998 within the range from 10 parts per million by volume (ppmv) to 500 ppmv. Finally, the long-term stability of the QEPAS system was evaluated using Allan deviation analysis, and the ultimate detection limit of ∼130 ppbv was reached for an optimum averaging time of ∼108 s at atmospheric pressure and ambient temperature.
      Citation: Applied Spectroscopy
      PubDate: 2019-08-02T03:47:17Z
      DOI: 10.1177/0003702819866468
  • Direct Measurements of Small Polar Impurities in Gasoline Mixtures Using
           Molecular Rotational Resonance Spectroscopy
    • Authors: Artressa L. Christophe, Jalon T. Barnes, Sylvestre Twagirayezu, Aleksandr Mikhonin, Matthew T. Muckle, Justin L. Neill
      First page: 1334
      Abstract: Applied Spectroscopy, Ahead of Print.
      This paper reports our efforts to determine whether rotational spectroscopy is a useful tool for petroleum analysis. These efforts include the use of a BrightSpec molecular rotational resonance (MRR) spectrometer, which operates in the 260–290 GHz frequency range, to record rotational spectra of small polar contaminants in commercial gasoline. The observed rotational spectra showed rich, but assignable, patterns due to the sensitivity of the MRR to only small polar compounds. Any interference from a complex hydrocarbon matrix, which in conventional chromatographic methods obscures signals from small polar contaminants, is nearly eliminated. In addition to the evident rotational spectrum of ethanol, the spectra of toluene, ethyl cyanide, and acetaldehyde have also been detected. A quantitative method for ethanol has been developed and demonstrated in this paper, whereas the specific analyses of the other polar impurities will be reported in the future. The validity of MRR to be used as an analytical instrument has been examined by constructing a standard linear curve using dilutions of ethanol in water. The linearity and percentage recovery parameters are satisfactory.
      Citation: Applied Spectroscopy
      PubDate: 2019-09-09T03:39:23Z
      DOI: 10.1177/0003702819859012
  • EXPRESS: Nondestructive Chemical Analysis of the Iron-Containing Protein
           Ferritin Using Raman Microspectroscopy
    • Authors: Carolin Hartmann, Martin Elsner, Reinhard Niessner, Natalia Ivleva
      Abstract: Applied Spectroscopy, Ahead of Print.

      Citation: Applied Spectroscopy
      PubDate: 2018-12-17T12:06:10Z
      DOI: 10.1177/0003702818823203
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