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Stark effect or coverage dependence? Disentangling the EC-SEIRAS vibrational shift of sulfate on Au(111)
摘要： Infrared spectroscopy is a widely employed analytical tool in (electrochemical) surface science as the spectra contain a wealth of information about the interaction of interfacial adsorbates with their environment. Separating and quantifying individual contributions, for example, of co-adsorbates, the substrate or electric field effects, on the overall spectral response, however, is often non-trivial as the various interactions manifest themselves in similar spectral behavior. Here, we present an experimental approach to differentiate between and quantify potential-induced coverage dependence and field-related Stark effects observed in a sulfate band shift of 93.5 ± 1.5 cm?1/V in electrochemical infrared spectra of the showcase sulfate/Au(111) interface. In combination with a simple linear model equation used to describe the potential-induced peak shift of the sulfate stretch vibration, we determine the coverage dependence contribution to be 15.6 ± 1.2 cm?1/θSO and the Stark effect to amount to 75.6 ± 2.7 cm?1/V. Our work provides a novel route to gain fundamental insight into interfacial adsorbate interactions in electrochemical surface science.
关键词： Stark effect,Infrared spectroscopy,sulfate/Au(111) interface,electrochemical surface science,coverage dependence
更新于2025-09-09 09:28:46
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Review on multi gas detector using infrared spectral absorption technology
摘要： To provide some references for researchers engaged in infrared multi gas detection, this study introduced the infrared multi gas detection system thoroughly from infrared light source, infrared detector, optical multiplexing structure, and detection method. Currently, the coherent source represented by quantum cascade laser has replaced the traditional incoherent source like thermal radiant infrared light source and became the dominant light source in infrared multi gas detection. Accordingly, the infrared photodetector is widely used. The optical multiplexing structure based on the “multiplexing thought” is the core of infrared multi gas detection system. It mainly includes the single-source multiplex detection structure and multi-source multiplexing detection structure. Nondispersive infrared spectroscopy, long optical distance spectroscopy, wavelength/frequency modulation spectroscopy, cavity enhancement spectroscopy, and photoacoustic spectroscopy are major detection methods used in the infrared multi gas detection. This has important significance to many fields, such as industrial and agriculture production, environmental monitoring, life science, etc.
关键词： optical multiplexing structure,infrared spectroscopy,infrared detector,Multi gas detection,infrared light source
更新于2025-09-04 15:30:14
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Development of a radiative transfer model for the determination of toxic gases by Fourier transform–infrared spectroscopy with a support vector machine algorithm
摘要： This report describes a radiative transfer model for Fourier transform-infrared (FT-IR) spectroscopy to create close-to-reality toxic gas spectra by reflecting the unique spectral responses of detectors and using the atmospheric radiative transfer code, MODTRAN. This system can be highly useful in overcoming the limitations for measuring toxic gases in open environments. The emulated gas spectra can be used to train support vector machine (SVM) for chemical gas detection. Its detection performance is evaluated with nerve agents (tabun, sarin, soman, and cyclosarin) and a simulant gas (sulfur hexafluoride) for indoor and outdoor experiments by using two off-the-shelf FT-IR gas detectors. The experimental results show that the proposed SVM algorithm successfully detected and classified targeted gases while reducing false negative and false positive detection rates.
关键词： support vector machine gas detection,Fourier transform infrared remote sensing,support vector machine,hyperspectral imaging,Fourier transform – infrared spectroscopy,stand-off detection
更新于2025-09-04 15:30:14
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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Connecting Organic and Physical Chemistry Students with Raman Spectroscopy
摘要： The profile of Raman spectroscopy may be elevated in the undergraduate chemistry curriculum by intentionally tying together students’ experiences in the organic and physical chemistry laboratories. In this way the valuable role Raman spectroscopy can play in structure elucidation is highlighted. The Committee on Professional Training of the American Chemical Society includes the category of optical molecular spectroscopy (e.g., IR, UV-Vis, Raman, and fluorescence spectroscopies) as an option in the panel of instruments required for certification. To the authors’ knowledge there are no Raman spectroscopy experiments that build directly on the analysis of compounds synthesized by students in a prior course for the intended purpose of scaffolding the curriculum. This chapter highlights the roles Raman spectroscopy may play in the determination of molecular structure when used in conjunction with other, more common techniques. Indeed, direct comparison to infrared spectroscopy holds the potential to reinforce that technique and its applications while introducing the study of Raman spectra. A set of three reaction products from electrophilic aromatic substitution, Diels-Alder, and aldol condensation (this including site-specific deuteration) is explored. All of these reactions are currently part of the organic chemistry curriculum. By combining analyses performed in organic chemistry with new laboratories written for the physical chemistry laboratory the authors hope to impress upon undergraduates the value of Raman spectroscopy in a context that builds on their previous experiences with other molecular spectroscopy methods.
关键词： structure elucidation,undergraduate chemistry curriculum,electrophilic aromatic substitution,Diels-Alder reaction,Raman spectroscopy,infrared spectroscopy,deuteration,physical chemistry,aldol condensation,organic chemistry
更新于2025-09-04 15:30:14
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Adaptive filtering of physiological noises in fNIRS data
摘要： The study presents a recursive least?squares estimation method with an exponential forgetting factor for noise removal in functional near?infrared spectroscopy data and extraction of hemodynamic responses (HRs) from the measured data. The HR is modeled as a linear regression form in which the expected HR, the first and second derivatives of the expected HR, a short?separation measurement data, three physiological noises, and the baseline drift are included as components in the regression vector. The proposed method is applied to left?motor?cortex experiments on the right thumb and little finger movements in five healthy male participants. The algorithm is evaluated with respect to its performance improvement in terms of contrast?to?noise ratio in comparison with Kalman filter, low?pass filtering, and independent component method. The experimental results show that the proposed model achieves reductions of 77% and 99% in terms of the number of channels exhibiting higher contrast?to?noise ratios in oxy?hemoglobin and deoxy?hemoglobin, respectively. The approach is robust in obtaining consistent HR data. The proposed method is applied for both offline and online noise removal.
关键词： State space model,Hemodynamic response (HR),Exponential forgetting,Recursive least squares estimation (RLSE),Real time estimation,Functional near?infrared spectroscopy (fNIRS)
更新于2025-09-04 15:30:14
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The role of near-infrared spectroscopy in the detection of vulnerable atherosclerotic plaques
摘要： Coronary artery disease is the leading cause of mortality worldwide. Most acute coronary syndromes are caused by a rupture of a vulnerable atherosclerotic plaque which can be characterized by a lipid-rich necrotic core with an overlying thin fibrous cap. Many vulnerable plaques can cause angiographically mild stenoses due to positive remodelling, which is why the extent of coronary artery disease may be seriously underestimated. In recent years, we have witnessed a paradigm shift in interventional cardiology. We no longer focus solely on the degree of stenosis; rather, we seek to determine the true extent of atherosclerotic disease. We seek to identify high-risk plaques for improvement in risk stratification of patients and prevention. Several imaging methods have been developed for this purpose. Intracoronary near-infrared spectroscopy is one of the most promising. Here, we discuss the possible applications of this diagnostic method and provide a comprehensive overview of the current knowledge.
关键词： vulnerable plaque,near-infrared spectroscopy,lipid-core plaque
更新于2025-09-04 15:30:14
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Relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists for display manufacture, studied by real-time Fourier transform infrared spectroscopy and quartz crystal microbalance methods
摘要： Photoresists are an indispensable technology used for manufacturing electronic devices such as displays and semiconductors. In this study, we investigated the relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists used for display manufacture using real-time Fourier transform infrared spectroscopy (FTIR) and quartz crystal microbalance (QCM) methods. To improve photoresist performance, it is important to understand the development mechanism of photoresists. Two kinds of polymers (a polymer with peeling-type dissolution and a polymer with a dissolution type with Case II diffusion) were used. 1,2-Octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide were used as photoinitiators. The dissolution was of the peeling type when the polymers were formulated as a typical cross-linking-type photoresist. With increasing conversion ratio of C=C double bonds, the rate of developer intake decreased and the impregnation threshold before the onset of peeling increased and then decreased. It was also found that the dissolution kinetics were affected by the radicals generated upon the decomposition of photoinitiators.
关键词： C=C double bond conversion,dissolution kinetics,quartz crystal microbalance,Photoresists,real-time Fourier transform infrared spectroscopy
更新于2025-09-04 15:30:14
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The effects of lumbar sympathectomy on bone and soft tissue haemodynamics of the leg recorded using near infrared spectroscopy: A case report
摘要： Near infrared spectroscopy (NIRS) is an established tool for the measurement of microvascular haemodynamics in different tissue types. This case report outlines the novel use of NIRS for measuring total oxygenation index (TOI) and relative oxygenated and deoxygenated haemoglobin concentration changes as markers of oxygenation and blood volume in muscle and bone tissue. In particular, NIRS is used to examine differences between the left and right leg in a participant who has experienced a permanent unilateral lumbar sympathectomy following an anterior lumbar intervertebral fusion. Anatomical sites at the lateral head of the gastrocnemius, tibial diaphysis and proximal tibia were investigated with NIRS during an arterial occlusion protocol at the distal femur. Consistent differences were observed between the sympathectomised left leg and the normal right leg. These included reduced baseline TOI, reduced deoxygenation rates during occlusion, and reduced reoxygenation rates post occlusion release in the sympathectomised leg at all anatomical sites. This case report demonstrates the potential of NIRS as a research tool for investigating the microvascular effects of lumbar sympathectomy. This may be useful for further investigation into the merit of chemical lumbar sympathectomy for the treatment of a variety of conditions, including hyperhidrosis and peripheral vascular disease.
关键词： Sympathectomy,Near infrared spectroscopy,Total oxygenation index,Muscle,Bone
更新于2025-09-04 15:30:14
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Flattened fiber-optic ATR sensor enhanced by silver nanoparticles for glucose measurement
摘要： This paper proposes a novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision. The flattened structure was designed to add the effective optical path length to improve the sensitivity. AgNPs were then deposited on the surface of the flattened area of the fiber via chemical silver mirror reaction for further improving the sensitivity by enhancing the infrared absorption. Combining the AgNPs modified flattened fiber ATR sensor with a CO2 laser showed a strong mid-infrared glucose absorption, with an enhancement factor of 4.30. The glucose concentration could be obtained by a five-variable partial least-squares model with a root-mean-square error of 4.42 mg/dL, which satisfies clinical requirements. Moreover, the fiber-based technique provides a pretty good method to fabricate miniaturized ATR sensors that are suitable to be integrated into a microfluidic chip for continuous glucose monitoring with high sensitivity.
关键词： Attenuated total reflection sensor,Mid-infrared spectroscopy,Flattened structure,AgNPs,Continuous glucose monitoring
更新于2025-09-04 15:30:14
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Onset Classification in Hemodynamic Signals Measured during Three Working Memory Tasks Using Wireless Functional Near-Infrared Spectroscopy
摘要： Wireless wearable functional near-infrared spectroscopy (fNIRS) has attracted growing attention as a candidate for real-life brain monitoring systems. It is important to determine the onsets at which neuronal activation is evoked by cognitive status in real-time analysis. We propose a machine learning approach for the classification of cognitive event onsets (CogEOs) in hemodynamic signals during three cognitive tasks. The approach does not require a threshold to be set or additional measurement for the rest state. A support vector machine is trained by labeled features obtained from the mean amplitude of hemodynamic changes and then predicts the type of onset points. The problems caused by the imbalance between CogEOs and non-event onsets (NonEO) are solved by oversampling the feature samples labeled by cognitive events. By oversampling, the classification accuracy from an average of five classification scores reaches 74%, 77%, and 75% for the simple arithmetic, 1-back and 2-back tasks. We achieve the best onset classification performance when the NonEOs are randomly distributed and when the subject is performing the 1-back task. Our study extends fNIRS to real-life applications by detecting the time point when brain activation starts among random observations using machine learning without additional triggers or threshold settings.
关键词： functional near-infrared spectroscopy,onset classification,and working memory,classification accuracy
更新于2025-09-04 15:30:14