Mid-infrared Optical Frequency Comb-based Fourier Transform Spectrometer for Broadband Molecular Spectroscopy

Optical frequency combbased Fourier transform spectroscopy has the features of broad spectral bandwidth,high sensitivity,andmultiplexed trace gas detection,which has valuable application potential in the fields of precision spectroscopy and trace gas detection.Here,we report the development of a mid-infrared Fourier transform spectrometer based on an optical frequency comb combined with a Herriott-type multipass cell.Using this instrument,the broadband absorption spectra of several important molecules,including methane,acetylene,water molecules and nitrous oxide,are measured by near real-time data acquisition in the 2800-3500 cm^(-1)spectral region.The achieved minimum detectable absorption of the instrument is 4.4×10^(-8)cm^(-1)·Hz^(-1/2)per spectral element.Broadband spectra of H_(2)0 are fited using the Voigt profile multispectral fitting technique and the consistency of the concentration inversion is 1%.Our system also enables precise spectroscopic measurements,and it allows the determination of the spectral line positions and upper state constants of N_(2)O in the(0002)-(1000)band,with results in good agreement with those reported by Toth[Appl.Opt.30,5289(1991)].

Detection of Broad Bean Diseases by Fourier Transform Infrared Spectroscopy Combined with Curve Fitting

Fourier transform infrared （FTIR） spectroscopy was used to study diseased leaves in broad bean. Results showed that the infrared spectra of different broad bean diseased leaves were similar, which were mainly made up of the vibrational absorption bands of protein,lipid and polysaccharide.There were minor differences in-cluding the spectral peak position, peak shape and the absorption intensity in the range of 1 800-1 300 cm-1. There were obvious differences among their second derivative spectra in the range of 1 800-1 300 cm-1. After the procedure of the Fourier self-deconvolution and curve fitting of health bean leaves and broad bean diseased leaves in the range of 1 700-1 500 cm-1, three sub-peaks were obtained at 1 550 cm-1 （protein amide Ⅱ band）, 1 605 cm-1 （lignin） and 1 650 cm-1 （protein amide I band）.The ratios of relative areas of the bands of amide Ⅱ, lignin, and amide I were 38.86%, 28.68% and 32.47% in the spectra of healthy leaves, respec-tively. It was distinguished from the diseased leaves （chocolate spot leaf： 15.42%, 42.98% and 41.61%, ring spot leaf：32.39%, 35.63% and 31.98%, rust leaf： 13.97%, 46.40% and 39.65%, yel owing leaf curl disease leaf： 24.01%,36.55% and 39.44%）. For sub-peak area ratios （A1 563/A1 605, A1 650/A1 605 and A1 563/A1 654）, those of four kinds of diseased leaves were smal er than that of healthy leaves, and there were also differences among four kinds of diseased leaves. The results proved that FTIR combining with curve fitting might be a potential y useful tool for detecting different kinds of broad bean diseases.

Retrieval algorithm of quantitative analysis of passive Fourier transform infrared (FTRD) remote sensing measurements of chemical gas cloud from measuring the transmissivity by passive remote Fourier transform infrared

Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of concentration measurement is based on the Beer-Lambert law. Unlike the active measurement, for the passive remote sensing, in most cases, the difference between the temperature of the gas cloud and the brightness temperature of the background is usually a few kelvins. The gas cloud emission is almost equal to the background emission, thereby the emission of the gas cloud cannot be ignored. The concentration retrieval algorithm is quite different from the active measurement. In this paper, the concentration retrieval algorithm for the passive FTIR remote measurement of gas cloud is presented in detail, which involves radiative transfer model, radiometric calibration, absorption coefficient calculation, et al. The background spectrum has a broad feature, which is a slowly varying function of frequency. In this paper, the background spectrum is fitted with a polynomial by using the Levenberg-Marquardt method which is a kind of nonlinear least squares fitting algorithm. No background spectra are required. Thus, this method allows mobile, real-time and fast measurements of gas clouds.

The role of fluid polarity in the swelling of sodium-montmorillonite clay:A molecular dynamics and Fourier transform infrared spectroscopy study

Swelling clays are found extensively in various parts of the world, and sodium-montmorillonite(NaMMT) is the main constituent of an expansive clay mineral. In this work, the swelling behavior of NaMMT clay with a wide range of organic fluids, high polar through low polar fluids, is studied using a combination of Fourier transform infrared(FTIR) technique and molecular dynamics(MD) simulations.The construction of the representative clayefluid models is carried out, and the nature of nonbonded interactions between clay and fluids is studied using MD. Our FTIR and MD simulations results suggest the significant nonbonded interactions between Na-MMT clay and polar fluids, such as formamide and water. The nonbonded interactions of Na-MMT with methanol and acetone are significantly less than those in Na-MMT with polar fluids. The interactions of the fluids with various entities of the clay such as Sie O, Fee OH, Mge OH, and Ale OH captured via the spectroscopy experiments and modeling provide a finer understanding of the interactions and their contributions to swelling. The MD simulations are able to capture the band shifts observed in the spectra obtained in the spectroscopy experiments. This work also captures the conformations of interlayer sodium ions with formamide, water, methanol, and acetone during swelling. These nonbonded interactions provide insight into the molecular mechanism that the polarity of fluids plays an important role in the initiation of interlayer swelling, alteration in the orientations, and evolution of microstructure of swelling clays at the molecular scale.

Quantitative Analysis of Lignocellulosic Components of Non-Treated and Steam Exploded Barley, Canola, Oat and Wheat Straw Using Fourier Transform Infrared Spectroscopy

Rapid and cost effective quantification of lignocellulosic components （cellulose, hemicelluloses and lignin） of agricultural biomass （barley, canola, oat and wheat） is essential to determine the effect of various pre-treatments （such as steam explosion） on biomass used as feedstock for the biofuel industry. Fourier Transformed Infrared （FTIR） spectroscopy was considered as an option to achieve this objective. Regression equations having R2 values of 0.89, 0.99 and 0.98 were developed to predict the cellulose, hemicelluloses and lignin compounds of biomass, respectively. The average absolute difference in predicted and measured cellulose, hemicellulose and lignin in agricultural biomass was 7.5%, 2.5%, and 3.8%, respectively.

Identification of Plant-Pathogenic Fungi Using Fourier Transform Infrared Spectroscopy Combined with Chemometric Analyses

Identification of plant-pathogenic fungi is time-consuming due to cultivation and microscopic examination and can be influenced by the interpretation of the micro-morphological characters observed.The present investigation aimed to create a simple but sophisticated method for the identification of plant-pathogenic fungi by Fourier transform infrared(FTIR)spectroscopy.In this study,FTIR-attenuated total reflectance(ATR)spectroscopy was used in combination with chemometric analysis for identification of important pathogenic fungi of horticultural plants.Mixtures of mycelia and spores from 27fungal strains belonging to nine different families were collected from liquid PD or solid PDA media cultures and subjected to FTIR-ATR spectroscopy measurements.The FTIR-ATR spectra ranging from 4 000to 400cm-1 were obtained.To classify the FTIRATR spectra,cluster analysis was compared with canonical vitiate analysis(CVA)in the spectral regions of3 050~2 800and 1 800~900cm-1.Results showed that the identification accuracies achieved 97.53%and99.18%for the cluster analysis and CVA analysis,respectively,demonstrating the high potential of this technique for fungal strain identification.

Rapid Method for the Determination of Total Monosaccharide in <i>Enterobacter cloacae</i>Strains Using Fourier Transform Infrared Spectroscopy

Fourier Transform Infrared Spectroscopy (FTIR) was used to quantify total monosaccharide content in the bacterium Enterobacter cloacae and several of its biofilm mutants. Bacterial biofilm samples were grown on trypticase soy agar, and 30 μL aliquots of aqueous sample bacterial plus biofilm were deposited into the center of barium fluoride crystals and dried at 50°C for 1-hour before being scanned by FTIR. The total amounts of monosaccharides were estimated using the absorbance of the mono-saccharide peak, 1192 - 958 cm–1, and normalized using the amide II peak, 1585 - 1483 cm–1. This method provided a linear correlation between the absorbance of the monosaccharide peak and concentration of monosaccharide in standard monosaccharides, fructose, glucose, mannose, and rhamnose, over a concentration range of 0.5 - 2.0 mg/mL.

GP Algorithm-Based Fourier Transform Infrared Spectrum Trend Term Removal Model

Trend term removal is a key step in Fourier transform infrared spectroscopy(FTIR)data pre-processing.The most commonly used least squares(LS)method,although satisfying the real-time requirement,has many problems such as highly correlated initial values of the expression parameters,the need to pre-estimate the trend term shape,and poor fitting accuracy at low signal-to-noise ratios.In order to achieve real-time and robust trend term removal,a new trend term removal method using genetic programming(GP)in symbolic regression is constructed in this paper,and the FTIR simulation interference results and experimental measurement data for common volatile organic compounds(VOCs)gases are analyzed.The results show that the genetic programming algorithm can both reduce the initial value requirement and greatly improve the trend term accuracy by 20%-30% in three evaluation indicators,which is suitable for gas FTIR detection in complex scenarios.

Fourier Transform Infrared Spectroscopic Study of Sodium Phosphate Solids and Solutions

Solids and solutions of sodium phosphates with various chain lengths have been studied by using the techniques of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and attenuated total reflection-Fourier transform infrared (ATR-ETIR) spectroscopy, respectively. A systematic study of the infrared spectra of the solid sodium phosphates has been conducted on the basis of the information available it? the literatures to establish the assignments of the infrared vibrations of the different groups in the phosphate molecules. The infrared spectra of the solutions of sodium phosphates have been analyzed according to the infrared study on the relevant solids, in conjunction with the study of the phosphate species distribution in solution on the basis of the acid-base reaction equilibria. The results obtained have revealed the correlations between the infrared absorption spectra and the structure of the different P-O groups in different kinds of phosphates and are useful in the analysis of phosphate solids and solutions widely used in the various operations of mineral processing.

Comparative Study on the Infrared Spectra of Straight Guard Hairs of Leopard Cat and Golden Cat

[Objective] The paper was to compare the infrared spectra of straight guard hairs of leopard cat and golden cat. [Method] The straight guard hairs of leopard cat and golden cat were detected and analyzed by FTIR （Fourier Transform Infrared Spectroscopy）. [Result] There was significant interspecific difference in the infrared spectra and second derivative spectra for the middle part of guard hair. An evident M-shaped bimodal absorption peak appeared in golden cat at 648 and 654 cm-1, respectively, while did not appear in leopard cat. The second derivative spec-tra of golden cat at wave numbers from 709 to 763 cm -1 were mainly unimodal peaks with strong peak intensity, while that of leopard cat mainly was M-shaped bi-modal absorption peak with weak peak intensity. It indicated that there was obvious difference in the structure of protein side chain in guard hairs of these two animals. [Conclusion] The FTIR analysis showed great application foreground in the study of animal hairs for interspecific identification.

模块化FTIR测定FCV用氢气痕量杂质

设计构建了用于质子交换膜燃料电池汽车(FCV)氢气痕量杂质的模块化FTIR分析表征平台,开发了适用于氢气痕量杂质的分析方法,无需处理一次进样,能够同时快速测定HCOOH、CO、CO_(2)、NH_(3)、H_(2)O、CH_(4)、C_(2)H_(4)、C_(2)H_(6)、HCHO等多种痕量级别杂质。考察了各含氢杂质分析的影响因素,精选了杂质物种定性区域,优化了定量方法,提出了实用性强的定量检出限,在降低了背景气和空白气纯度的要求也能确保限值浓度准确测定。九种杂质的计算方法检出限达到ASTM D7653-18参考值,其定量限也均低于ISO 14687:2019相应的限值,定量线性范围约2个数量级,相关系数均大于0.999,准确度和精密度均不高于10%,通过ISO 21087:2019规定的方法适用性验证规则,满足ISO 14687:19相应的质控标准。根据不同场景需求,样品模块、气体净化控制模块、配气模块、红外分析模块和尾气处理模块可以有机结合并具有良好的实用性和扩展性,尾气处理后氢气浓度可降至100μmol·mol^(-1)以下排放,满足安全绿色环保的要求。与实验室其他参考方法测定值有较好的一致性,并已在FCV氢气工业生产样品质量检测中得到应用,它将从实验室离线方法逐步发展成为适用于工业不同场景的在线方法,这对燃料级氢气品质体系的建立、纯化技术的推广应用及燃料电池催化剂新材料开发均具有意义。

基于移动平台的便携式FTIR灾害现场气体检测技术

傅里叶红外光谱技术(FTIR)的引入极大地提升了气体的检测速度和准确性。然而在石油化工泄露和爆炸、森林火灾等突发危险现场,存在着人力无法现场检测的情况。为了应对这种场景,开发了基于移动平台的便携式FTIR灾害现场气体检测方法。通过将云服务器和树莓派的优势相结合实现远程操作移动平台,将搭载便携式FTIR光谱仪的移动平台远程操作驶入现场,并及时通过4G/5G模块传回现场位置数据、视频数据和光谱气体浓度数据。最后,在野外基地利用该平台进行了实测,对CO_(2)、CO、SO_(2)、C_(6)H_(6)等多种污染气体进行了检测,结果验证了该系统在野外工况下的可靠性。本工作为FTIR光谱仪或其他光谱类检测系统在移动平台上的集成应用提供了思路和解决方案。

IR-EcoSpectra: Exploring sustainable ex situ and in situ FTIR applications for green chemical and pharmaceutical analysis

In various industries,particularly in the chemical and pharmaceutical fields,Fourier transform infrared spectroscopy(FTIR)spectroscopy provides a unique capacity to detect and characterise complex chemicals while minimising environmental damage by minimal waste generation and reducing the need for extensive sample preparation or use of harmful reagents.This review showcases the versatility of ex situ and in situ FTIR applications for substance identification,analysis,and dynamic monitoring.Ex situ FTIR spectroscopy’s accuracy in identifying impurities,monitoring crystallisation processes,and regulating medication release patterns improves product quality,safety,and efficacy.Furthermore,its quantification capabilities enable more effective drug development,dosage procedures,and quality control practices,all of which are consistent with green analytical principles.On the other hand,in situ FTIR spectroscopy appears to be a novel tool for the real-time investigation of molecular changes during reactions and processes,allowing for the monitoring of drug release kinetics,crystallisation dynamics,and surface contacts,as well as providing vital insights into material behaviour.The combination of ex situ FTIR precision and in situ FTIR dynamic capabilities gives a comprehensive analytical framework for developing green practices,quality control,and innovation in the chemical and pharmaceutical industries.This review presents the wide range of applications of ex situ and in situ FTIR spectroscopy in chemical,pharmaceutical and medical fields as an analytical green chemistry tool.However,further study is required to fully realise FTIR’s potential and develop new applications that improve sustainability in these areas.

Assessment of portable FTIR and Raman spectroscopy for the detection of 2,3-dimethyl-2,3-dinitrobutane(DMDNB)in plastic explosives

The Marplex Convention was established to prevent the manufacture of unmarked plastic explosives and stipulates that a volatile detection agent must be added at the time of manufacture.However,to-date,laboratory testing remains the internationally accepted practice for identifying and quantifying the taggants stipulated in the Convention.In this project,portable FTIR and Raman instruments were tested for their ability to detect 2,3-dimethyl-2,3-dinitrobutane(DMDNB),the chemical marker incorporated in plastic explosives that are manufactured within Australia.While both FTIR and Raman instruments detected solid DMDNB(98%purity),field analysis of plastic explosives at an Australian Defence establishment showed that both FTIR and Raman spectra were matched the relevant explosive(RDX or PETN),rather than the DMDNB taggant.For all three plastic explosives tested,the concentration of DMDNB was measured by SPME-GC-MS to be between 1.8 and 2%,greater than the minimum 1%concentration stipulated by the Marplex Convention.Additional testing with a plastic explosive analogue confirmed that the minor absorption peaks that would characterize low concentrations of DMDNB were masked by absorption bands from other compounds within the solid.Thus,while both FTIR and Raman spectroscopy are suitable for detection of plastic explosives,neither rely on the presence of DMDNB for detection.It is likely that similar results would be found for other taggants stipulated by the Marplex Convention,given they are also present in concentrations less than 1%.

Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy

Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.

Thermal,infrared spectroscopy and molecular modeling characterization of bone:An insight in the apatite-collagen type I interaction

An insight into the interaction of collagen type I with apatite in bone tissue was performed by using differential scanning calorimetry, Fourier transform infrared spectroscopy, and molecular modeling. Scanning electron microscopy shows that bone organic content incinerate gradually through the different temperatures studied. We suggest that the amide regions of the type I collagen molecule (mainly C=O groups of the peptide bonds) will be important in the control of the interactions with the apatite from bone. The amide I infrared bands of the collagen type I change when interacting to apatite, what might confirm our assumption. Bone tissue results in a loss of thermal stability compared to the collagen studied apart, as a consequence of the degradation and further combustion of the collagen in contact with the apatite microcrystals in bone. The thermal behavior of bone is very distinctive. Its main typical combustion temperature is at 360°C with a shoulder at 550°C compared to the thermal behavior of collagen, with the mean combustion peak at ca. 500°C. Our studies with molecular mechanics (MM+ force field) showed different interaction energies of the collagen-like molecule and different models of the apatite crystal planes. We used models of the apatite (100) and (001) planes;additional two planes (001) were explored with phosphate-rich and calcium-rich faces;an energetic preference was found in the latter case. We preliminary conclude that the peptide bond of collagen type I is modified when the molecule interacts with the apatite, producing a decrease in the main peak from ca. 500°C in collagen, up to 350°C in bone. The combustion might be related to collagen type I, as the ΔH energies present only small variations between mineralized and non-mineralized samples. The data obtained here give a molecular perspective into the structural properties of bone and the change in collagen properties caused by the interaction with the apatite. Our study can be useful to understand the biological synthesis of minerals as well as the organic-inorganic interaction and the synthesis of apatite implant materials.

当归痛风方对小鼠高尿酸血症肾病的FTIR研究

傅里叶变换红外光谱(FTIR)是鉴别物质和分析物质结构的有效手段,可对样品进行定性和定量分析,广泛应用于医药化工等众多领域。FTIR作为一种操作简便、实用、准确率高和费用低的鉴别方法,如今已经普遍应用于各种药品检验中,而有关其应用于药理研究中还非常少,目前仅有采用红外光谱分析法对各种肿瘤组织进行研究的报道。高尿酸血症肾病是人体血尿酸升高后,过高的尿酸负荷超过肾脏的清除能力,尿酸结晶沉积于集合管、肾盂和尿道等。采用FTIR技术评价高尿酸血症肾病模型,并评价药物的药效,具有一定的可行性。该实验为探讨FTIR评价高尿酸血症肾病模型和当归痛风方疗效的科学性,将60只KM小鼠随机分为6组,正常对照组、模型组、阳性对照组和当归痛风方低、中、高组,采用氧嗪酸钾复制高尿酸血症肾病模型,灌胃当归痛风方,检测血清UA、尿液UA、血清CRE、尿液CRE、血清IL-1β和肾脏IL-1β、肾脏FTIR谱图等,并观察肾脏的病理变化。结果表明模型组各项指标与正常组比较有统计学意义(p<0.05),当归痛风方高剂量组的血清UA、血清CRE、血清IL-1β和肾脏IL-1β等与模型组比较且有统计学意义(p<0.05)。当归痛风方高剂量组肾脏的病理变化有所改善,无炎性细胞浸润,管腔内无管型,说明对肾损伤具有保护作用。各组FTIR谱有明显的差异,模型组的强度均低于正常组,阳性对照组和当归痛风方高剂量组谱接近正常组,进一步说明当归痛风方对肾损伤具有保护作用。研究表明FTIR可以作为一种简便快捷灵活经济的评价动物模型及药物疗效的方法之一,也为高尿酸血症肾病模型及有效药物的筛选提供了一个有意义的技术手段。该实验拓展了FTIR检测方法的使用范围。

红外调制光致发光光谱技术:从宽波段覆盖到微区高通量测量

光致发光光谱能够揭示半导体材料带隙、杂质能级等电子结构信息,还可以分析界面、载流子寿命、量子效率,在紫外-近红外波段得到广泛应用.在约4μm以长红外波段,由于热背景干扰强、光致发光信号弱、探测能力低,光致发光光谱研究长期受限.本文介绍了利用傅里叶变换光谱仪测量光致发光光谱的常规方法,简述了为突破红外波段困境于1989年提出、历经20多年发展的连续扫描傅里叶变换双调制光致发光光谱方法及所受机理局限;分析了2006年报道的基于步进扫描傅里叶变换光谱仪的红外调制光致发光光谱方法的抗干扰、灵敏度、信噪比优势,列举了国际上诸多研究组对红外调制光致发光光谱方法有效性的例证和以此取得的应用研究进展;总结了近年来宽波段、高通量扫描成像和空间微区分辨红外调制光致发光光谱测试方法发展以及从0.56-20μm可见-远红外宽波段覆盖到千级通道光谱高通量检测、2-3μm微区分辨红外调制光致发光光谱技术进步,列举了应用研究稀氮/稀铋量子阱、HgCdTe外延膜、InAs/GaSb超晶格等可见-远红外半导体材料阶段结果和合作研究典型进展.本文展现了红外调制光致发光光谱方法先进性和宽波段、高通量扫描成像与空间微区分辨光谱测试方法有效性,预见了未来进一步应用研究方向.

用FTIR光谱仪测量排气系统中红外光谱辐射强度的方法

通过理论分析及实验研究讨论了傅立叶变换红外(FTIR)光谱仪测量排气系统中红外光谱辐射强度过程中误差产生的原因,设计了一套简易有效的测量方法.用此方法测量了黑体和热喷流的光谱辐射强度.结果表明:该测量方法能够有效地获得排气系统的中红外光谱辐射强度,具有工程实用价值.

铬诱导植物根细胞壁化学成分变化的FTIR表征

随着制革、电镀等行业的发展,铬污染已成为严重的环境问题而受到人们的关注。铬在植物体内主要积累于根部,植物根细胞壁化学变化与金属元素在植物体内的蓄积行为有密切关系。与其他方法比较,应用OMNI采样器-FTIR直接测定法表征细胞化学成分变化具有简便、快速和准确的优点。文章用FTIR对凤眼莲(Eichhornia crassipes)和空心莲子草(Alternanthera philoxeroides)根细胞壁进行了测定、分析和指认,并利用半定量分析方法研究了铬处理和对照处理下根细胞壁红外光谱的差异。结果表明,铬处理的凤眼莲和空心莲子草根细胞壁上的—OH向低频分别发生了20和6 cm-1的位移,同时凤眼莲的根细胞壁上—OH和自由羧基COO-等吸附位点数目较对照均有所增加,而空心莲子草则相反。说明这些基团与铬的结合密切相关,进一步解释了凤眼莲耐铬及其在根部积累铬的机理,说明FTIR在监测逆境诱导植物化学成分变化和环境绿色修复方面具有广泛的应用前景。