Applied Spectroscopy最新文献

{"title":"Complex-Valued Chemometrics in Spectroscopy: Classical Least Squares Regression.","authors":"Thomas G Mayerhöfer, Oleksii Ilchenko, Andrii Kutsyk, Jürgen Pop","doi":"10.1177/00037028251343908","DOIUrl":"https://doi.org/10.1177/00037028251343908","url":null,"abstract":"<p><p>We present the first implementation of complex-valued classical least squares (CLS) regression in spectroscopy. Although the results indicate that complex-valued CLS does not outperform methods that utilize only the more suitable part of the complex refractive index spectra, it includes an error detection feature that enables a self-correction mechanism. This mechanism decreases the mean absolute error (MAE) to approximately 26% relative to using only the mid-infrared (MIR) absorption index (<i>k</i>) spectra for CLS, and to about 46% relative to using only the MIR refractive index (<i>n</i>) spectra of benzene-toluene mixtures. For benzene-cyclohexane mixtures, the MAE was reduced to approximately 75% relative to the <i>k</i> spectra and 58% relative to the <i>n</i> spectra. In contrast, for benzene-carbon tetrachloride (CCl₄) mixtures, i.e., a system that exhibits particularly large deviations from Beer's law, no improvement over the <i>n</i> spectra was observed; the <i>n</i>-based MAE was 81% relative to the <i>k</i> spectra. These percentages may further vary based on the complexity of the system, the spectral regions selected for CLS and the corresponding deviations from Beer's approximation.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251343908"},"PeriodicalIF":2.2,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144141133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the Use of Fourier Transform Raman Spectroscopy for Pollen Chemical Characterization.","authors":"Florian Muthreich, Valeria Tafintseva, Boris Zimmermann, Achim Kohler, Carlos M Vila-Viçosa, Alistair W R Seddon","doi":"10.1177/00037028251334405","DOIUrl":"https://doi.org/10.1177/00037028251334405","url":null,"abstract":"<p><p>Vibrational spectroscopy is gaining popularity for understanding ecological and evolutionary patterns in plants, particularly in relation to the analysis of pollen grains. So far, Fourier transform infrared spectroscopy (FT-IR) has been the main approach used to classify pollen grains based on chemical variations. However, FT-IR may be less suitable for detecting differences in the pollen grain exine, mainly composed of sporopollenin. In contrast, Raman spectroscopy has increased sensitivity for the main chemical components found within sporopollenins. We compare the classification performance and chemical information provided by FT-IR and FT-Raman using a large dataset of <i>Quercus</i> L. pollen, comprising five species in three sections: (i) <i>Cerris</i>: <i>Q</i>. <i>suber</i>, (ii) <i>Ilex</i>: <i>Q. coccifera</i>, <i>Q. rotundifolia</i>, and (iii) <i>Quercus</i>: <i>Q. robur</i>, <i>Q. faginea</i>). Here, we used multiblock sparse partial least squares discriminant analyses (MB-sPLS-DA) analyses to directly compare the two infrared methods. Both FT-IR and FT-Raman successfully classified <i>Quercus</i> pollen to section level (100% accuracy). At the species level our models achieved ∼90% accuracy for FT-Raman and FT-IR separately and in the combined multiblock model. The multiblock results showed an increased number of sporopollenin peaks observed in FT-Raman spectra as compared to FT-IR. These peaks are also of a higher importance for classification. Results also showed differences in the types of vibrations that are of diagnostic value for the two infrared methods. CH₂ deformations are more important in FT-Raman, while C-O-C, C-O, and C = O stretches are more important for FT-IR-based identification of pollen. These vibrations are indicators of carbohydrates, proteins and lipids. FT-Raman provides equally successful diagnostic potential to FT-IR, but uses more chemical information based on variations in sporopollenin chemistry than FT-IR. We suggest that the combined analysis of FT-IR and FT-Raman using multiblock analysis has great potential for classification.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251334405"},"PeriodicalIF":2.2,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144126427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum Fourier Transform Infrared Spectroscopy: Evaluation, Benchmarking, and Prospects.","authors":"Paul Gattinger, Andreas W Schell, Sven Ramelow, Markus Brandstetter, Ivan Zorin","doi":"10.1177/00037028251340945","DOIUrl":"https://doi.org/10.1177/00037028251340945","url":null,"abstract":"<p><p>Sensing with undetected photons has enabled new, unconventional approaches to Fourier transform infrared spectroscopy (FT-IR). Leveraging properties of non-degenerate entangled photon pairs, mid-infrared (mid-IR) information can be accessed in the near-infrared (near-IR) spectral domain to perform mid-IR spectroscopy with silicon-based detection schemes. Here, we address practical aspects of vibrational spectroscopy with undetected photons using a quantum FT-IR (QFT-IR) implementation. The system operates in the spectral range from around 3000 cm^-1 to 2380 cm^-1 (detection at around 12 500 cm^-1) and possesses only 68 pW of mid-IR probing power for spectroscopic measurements with a power-dependence of the signal-to-noise ratio of 1.5 × 10⁵ mW^-1/2. We evaluate the system's short- and long-term stability and experimentally compare it to a commercial FT-IR instrument using Allan-Werle plots to benchmark our QFT-IR implementation's overall performance and stability. In addition, comparative qualitative spectroscopic measurements of polymer thin films are performed using the QFT-IR spectrometer and a commercial FT-IR with identical resolution and integration times. Our results show under which conditions QFT-IR can practically be competitive or potentially outperform conventional FT-IR technology.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251340945"},"PeriodicalIF":2.2,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144109641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Errata: Azimuth Angle Dependence of Polarized Infrared Spectra of Injection-Molded Polyoxymethylene.","authors":"","doi":"10.1177/00037028251340939","DOIUrl":"https://doi.org/10.1177/00037028251340939","url":null,"abstract":"","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251340939"},"PeriodicalIF":2.2,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144109591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Thin Silicone Films on Opaque Solid Surfaces Using Coherent Raman Scattering Imaging.","authors":"Julian Naser, George Sarau, Jan Wrege, Silke Christiansen","doi":"10.1177/00037028251339495","DOIUrl":"https://doi.org/10.1177/00037028251339495","url":null,"abstract":"<p><p>The measurement of thin films with a thickness in the nanometer range is challenging because it requires extensive sample preparation, vacuum condition, long measurement times or using test inks that additionally contaminate the surface. The detection of those films is crucial for production processes that rely on a boundary layer to create a proper interface like adhesive bonding, coating, or lithography in various industries like automotive, solar, energy storage and semiconductor manufacturing. Consequently, there is a need for quick, reliable measurement techniques with high sensitivity to ensure the technical cleanliness of the opaque surface. In this paper the feasibility of epi-detection with coherent Raman scattering (CRS) Imaging is investigated on different substrate materials and demonstrated to be a method for fast scanning of large nontransparent surfaces including chemical fingerprinting of the substances atop. Therefore, various samples with low surface energy filmic contaminations from polysiloxanes are produced and investigated with CRS Imaging, a technique mostly applied to biological samples with the novel use demonstrated here for surface contamination monitoring in material sciences.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251339495"},"PeriodicalIF":2.2,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144109601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-Angle Averaging Approach for Measuring the Coating Thickness on Thin Transparent Polymer Films.","authors":"Friederike Münch, Benedikt Hauer, Ingo Breunig, Daniel Carl","doi":"10.1177/00037028251334152","DOIUrl":"https://doi.org/10.1177/00037028251334152","url":null,"abstract":"<p><p>Polymer films with a thickness in the two-digit micrometer range are coated with nanometer-thin oxide layers in roll-to-roll coating systems. The coating improves the properties of the film, such as gas or water permeation. Maintaining a sufficiently large coating thickness is crucial to ensure its barrier function; thus, inline quality control of the thickness is indispensable. For this purpose, we have developed a sensing principle that addresses specific absorption bands of the coating via a reflection measurement in the infrared spectral range. However, for thin and weakly absorbing polymer substrates, light is reflected not only by the coating and the surface of the polymer. Partly it is also transmitted and reflected by the backside of the film, leading to interference effects that significantly affect the measurement signal. As industrial films vary in thickness by several percent and their exact values are unknown, determining the thickness of an oxide coating is hindered. In this paper, we demonstrate an approach for measuring coating thickness on such varying polymer films by averaging the interferences obtained at multiple angles of incidence. Calculations and measurements on industrial film samples indicate the effectiveness of our approach. It produces results with <math><mo>±</mo><mn>2</mn></math> nm precision and <math><mo>±</mo><mn>5</mn></math> nm accuracy for a thickness in the range of 5-100 nm. Furthermore, we discuss a possible implementation of this approach in an inline measurement system by fulfilling its requirements, for example, versatility and compactness.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251334152"},"PeriodicalIF":2.2,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144075614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization and Identification of Natural Amorphous Rocks Using Infrared, Raman, and Low-Frequency Raman Spectroscopy, Including the Application of Boson Peaks.","authors":"Kohei Tamura, Motohiro Tsuboi, Kuniyuki Furukawa, Ken-Ichi Akao, Harumi Sato, Yukihiro Ozaki","doi":"10.1177/00037028251333469","DOIUrl":"https://doi.org/10.1177/00037028251333469","url":null,"abstract":"<p><p>In this study, Raman spectra (3700-10 cm^-1) and attenuated total reflection infrared-far-infrared (ATR-IR/FIR) spectra (4000-50 cm^-1) including low-frequency region were measured for amorphous rocks, which were five types of obsidians whose formation ages and sources are different and pitchstone to clarify the differences in water content (free and bound water species), their Si-O bonds and possible linkage with a metal ion, and the mean atomic volume. In order to explore these points, we focused on infrared (IR) absorptions of hydroxyl (OH) groups that is observed in the 4000-3000 cm^-1 region, those of Si-O bond that is identified in the 1300-850 cm^-1 region and a Boson peak that appears in a low-frequency region of Raman spectra, respectively. IR absorption of Si-O stretching was detected for all samples and that of OH stretching and H-O-H bending was also detected in some rocks. Therefore, using IR spectroscopy was useful to discriminate each rock based on the water content and the environment of Si-O bonds. On the other hands, a Boson peak could be detected for the low-frequency region below 60 cm^-1 of Raman spectra, which appears in amorphous solids. This study is the first finding that the Raman shift of Boson peak was different among similar natural glassy rocks from multiple sources and it means that the mean atomic volume of samples was different. In addition, sharp bands of Raman scattering which came from inorganic substances such as feldspar helped to identify ingredients in samples. As a results, we made clear that using both IR and Raman including low-frequency regions is effective to identify the same types of natural amorphous rocks.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028251333469"},"PeriodicalIF":2.2,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143955092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shortwave Infrared Hyperspectral Imaging to Detect Contaminants in the U.S. Food Supply.","authors":"David M Malakauskas, Hongjian Ding, Ben P Berman, Nap Thantu, Kevin L Karem, Victoria M Gammino","doi":"10.1177/00037028241301089","DOIUrl":"10.1177/00037028241301089","url":null,"abstract":"<p><p>The U.S. Food and Drug Administration (FDA) ensures the safety of the nation's food supply using sampling and laboratory analysis of imported and domestic foods. Accurate detection and identification of extraneous filth elements in inspected food samples is critical in producing evidence for regulatory decision-making. As part of ongoing efforts to increase the efficiency and accuracy of data collection, to better inform regulatory decision-making, scientists at the FDA have been exploring the application of emerging imaging technologies. To this end, we tested the ability of shortwave infrared (SWIR) hyperspectral image analysis to simultaneously detect and identify filth elements from a variety of chemically digested single- and multiple-ingredient food matrices. We tested five stored-product beetle species on a background of four different food matrix types. Our analyses successfully detected whole beetles and fragments as small as 0.65 mm in 95% of samples. All beetle species tested were accurately detected from the background matrices, and initial classification results show identification to genus. Our results show that SWIR spectral image analysis is a very promising technology for application in the detection and identification of filth elements in food products in a regulatory context and further development has the potential to increase analytical efficiency at FDA regulatory labs.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"872-878"},"PeriodicalIF":2.2,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142778721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alternating and Modified Alternating Least Squares Applied to Raman Spectra of Finished Gasolines.","authors":"Collin G White, Thomas M Hancewicz, Ayuba Fasasi, Junior Wright, Barry K Lavine","doi":"10.1177/00037028241292649","DOIUrl":"10.1177/00037028241292649","url":null,"abstract":"<p><p>Extraction of components from individual refinery streams (e.g., reformates and alkylates) in finished gasoline was undertaken using Raman spectroscopy to characterize the chemical content of the finished product. Modified alternating least squares (MALS) was used for separating Raman spectroscopic data sets of the finished product into its pure individual components. The advantages of MALS over alternating least squares (ALS) for multicomponent resolution are highlighted in this study using three Raman spectroscopic data sets which provide a suitable benchmark for comparing the performance of these two methods. MALS is superior to ALS in terms of accuracy and can better resolve components than ALS, and it is also more robust toward collinear data. Finally, components near the noise level usually cannot be extracted by ALS because of instability when inverting the covariance structure which inflates the noise present in the data. However, these same components can be extracted by MALS due to the stabilization of the least squares regression with respect to the matrix inversion using modified techniques from ridge regression.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"808-815"},"PeriodicalIF":2.2,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142602885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of Orthophosphate and Orthovanadate in Aqueous Solution Using Polarized Raman Spectroscopy.","authors":"Wolfram Rudolph","doi":"10.1177/00037028241275107","DOIUrl":"10.1177/00037028241275107","url":null,"abstract":"<p><p>Polarized Raman spectroscopy was used to analyze aqueous solutions of sodium orthophosphate and orthovanadate over a wide concentration range (0.00891-0.702 mol/L) at 23 °C. The isotropic scattering profiles were obtained by measuring polarized Raman scattering spectra. Furthermore, R-normalized spectra were calculated and presented. The tetrahedral ions, VO₄^3-(aq) and PO₄^3-(aq), demand four Raman active bands which have been subsequently characterized and assigned. For the PO₄^3-(aq) ion, the deformation modes ν₂(e) and ν₄(f₂) appear at 415 and 557 cm^-1, and these modes are depolarized. In the P-O stretching region, the strongest Raman band appears at 936.5 cm^-1, which is totally polarized with a depolarization ratio (ρ-value) of 0.002. The broad and depolarized mode at 1010 cm^-1 constitutes the antisymmetric stretching band ν₃(f₂). The Raman spectrum of VO₄^3- shows two depolarized deformation modes ν₂(e) and ν₄(f₂) at 327 and 345.6 cm^-1, which are severely overlapped. These bands are very weak. The strongest band in the Raman spectrum of VO₄^3-(aq) is the symmetric stretching mode ν₁(a₁) at 820.2 cm^-1 which is totally polarized with a ρ-value at 0.004. The depolarized antisymmetric stretching mode ν₃(f₂) appeared at 785 cm^-1 as a broad and weak band. Both anions are strongly hydrated and showed extensive hydrolysis in an aqueous solution. Orthovanadate is a much stronger base than orthophosphate in aqueous solution. Therefore, a large amount of NaOH was used to suppress the hydrolysis of VO₄^3-(aq) sufficiently, so, it was possible to characterize the VO₄^3- modes. Quantitative Raman spectroscopy was applied to follow the hydrolysis of PO₄^3- over a wide concentration range from 0.00891 to 0.592 mol/L. The hydrolysis data allowed the calculation of the p<i>K</i>_a3 value for H₃PO₄ to be 12.330 ± 0.02 (25 °C). The hydrolysis of the VO₄^3- ion is ∼21 times larger than that of the PO₄^3-. The p<i>K</i>_a3 value for H₃VO₄ is estimated to be 13.65 ± 0.1 (25 °C).</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"829-841"},"PeriodicalIF":2.2,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142139139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}