Gas phase reaction rate measurements in Fourier transform mass spectrometry

Determination of the concentration of neutral polycyclic aromatic hydrocarbon molecules in the mass spectrometer for reaction rate measurement is investigated. Copyright 1999 John Wiley & Sons, Ltd.     

Study of the far infrared optical properties of KI by dispersive Fourier transform spectrometry

The optical constants of KI have been determined in the far infrared at 200 and 300K by dispersive Fourier transform spectrometry and used to calculate the imaginary part of the anharmonic self-energy of the qo transverse optic mode. The overall agreement, both quãlitatively and quantitatively, with calculations by Berg and Bell and by Edridge and Kembry which include contributions from cubic anharmonicity is good.     

Continuous measurements of stable carbon isotopes in CO2 with a near-IR laser absorption spectrometer

A near-IR laser absorption spectrometer using a technique of wavelength modulation spectroscopy is used to measure stable carbon isotope ratios of ambient CO₂ (δ¹³C) via the absorption lines ¹²CO₂ R(17) (2ν₁ + ν¹₂ − ν¹₂ + ν₃) at 4978.205 cm⁻¹ and ¹³CO₂ P(16) (ν₁ + 2ν₂ + ν₃) at 4978.023 cm⁻¹. The isotope ratios are measured with a reproducibility of 0.02‰ (1σ) in a 130-s integration time over a 12-h period. The humidity effect on δ¹³C values has been evaluated in laboratory experiments. The δ¹³C values of CO₂ in ambient air were measured continuously over 8 days and agreed well with those from isotope ratio mass spectrometry of canister samples. The spectrometer is thus capable of real-time, in situ measurements of stable carbon isotope ratios of CO₂ under ambient conditions.     

应用红外光谱技术鉴别中药麝香的真伪

采用傅里叶变换红外(FTIR)光谱法并结合二阶导数技术,测定了中药天然麝香及其伪品的红外光谱.结果表明:天然麝香的主要特征峰为3 284,2 923,2 851,1 655,1 546,1 400,1 038 cm-1等吸收峰,分别代表蛋白质、大环酮类和甾体类等主要成分;与天然麝香相比,麝香伪品的红外光谱的吸收的位置和强度有明显差异,可被容易区分;天然麝香、市售麝香及人工麝香的谱图相似性较高,尤其是人工麝香与天然麝香极其相似,难以区分;采用傅里叶二阶导数谱,提高了谱图分辨率,可直观有效地鉴别正品麝香.该方法具有快速、灵敏、直观、无损等特点,可为名贵药材的来源与真伪鉴别提供了新的手段.     

利用开放光路傅里叶变换红外方法监测地表臭氧含量及分析

基于自研傅里叶变换红外光谱仪设计实现了开放光路臭氧在线监测系统,将计算机合成背景光谱方法与非线性最小二乘方法相结合进行定量分析,利用HITRAN数据库信息和仪器线型合成背景光谱,通过非线性最小二乘法反演出臭氧浓度,提高了测量精度和检测限,讨论了系统检测限测最方法,在16次平均情况下系统检测限达到1.42 nmol·mo...     

Fourier transform infrared spectra of the FO2 radical

Six infrared bands of FO₂ have been measured at high resolution using a fast-flow long-path absorption cell and a Fourier transform spectrometer. The bands have been analyzed to obtain accurate band origins, as well as rotational, centrifugal distortion, and spin-rotation parameters. In order of increasing wavenumber they are ν₃ at 579 cm⁻¹, ν₂ + ν₃ at 940 cm⁻¹, 2ν₃ at 1142 cm⁻¹, ν₁ at 1487 cm⁻¹, ν₂ + 2ν₃ at 1496 cm⁻¹, and 2ν₁ at 2948 cm⁻¹. Only ν₃ has been studied previously (by C. Yamada and E. Hirota, J. Chem. Phys. 80, 4694–4700 (1984)); the other bands are rotationally analyzed here for the first time. The ν₁ and ν₂ + 2ν₃ vibrations were found to be strongly mixed by Coriolis- and Fermi-type interactions and were thus analyzed simultaneously. 2ν₁ was also observed to be perturbed, but the perturbations were not analyzed. FO₂ now becomes one of the best-characterized unstable free radicals in terms of its rotation-vibration structure.     

g-factor measurements in stable Hg isotopes

The g-factor of the first 2⁺ state in¹⁹⁸Hg,²⁰⁰Hg and²⁰²Hg has been measured using the thin foil Transient Field technique. The values were calibrated to the known g-factor of the first 5/2⁻ state in¹⁹⁹Hg. The levels were Coulomb excited by 217 MeV nickel ions with gadolinium acting as ferromagnetic medium. The obtained values are rather constant and contradict a previously observed dip at²⁰⁰Hg. Two other g-factors have been remeasured in¹⁹⁹Hg.     

Open-path Fourier transform infrared spectrometry characterization of low temperature combustion gases in biomass fuels

Accurate determination of gas concentration emitted during thermal degradation (pyrolysis) of biomass in forest fires is one of the keypoints in recent research on physical-based fire spread models. However, it is a very cumbersome task not well solved by classical invasive sensors and procedures. In this work, a methodology to use open-path Fourier transform-based infrared (OP-FTIR) spectrometry has been applied as a remote sensing technique that permits in situ, non-intrusive and simultaneous measurements. Main gaseous by-products (CO, CO₂, CH₄ and NH₃) have been measured and quantified in terms of path-integrated concentrations. Different emission ratios have been determined for the species under study. These results can help to simplify the modelling of pyrolysis processes inside the physical-based models for fire spread.     

激光单稳频指标的激光计量红外光谱仪精度分析

在傅里叶变换红外光谱仪中,采用激光计量光程差可提高光谱的测量精度。激光波长作为光程差测量的基准单位,其线宽和稳频特性直接决定了光程差的误差,进而影响光谱的测量精度。根据光谱仪的干涉原理,通过傅里叶逆变换和误差分析方法,建立了光谱测量相对误差与激光单稳频指标之间的理论模型,并对该模型进行了仿真计算。结果证明,该模型可作为设计激光计量光程差光谱仪系统的理论依据。     

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.     

基于傅里叶变换红外光谱技术测量大气中CO_2的稳定同位素比值

长期监测大气中CO_2及其稳定同位素不仅可以获得CO_2源和汇信息,还可以确定不同排放源对大气中CO_2的贡献.傅里叶变换红外光谱技术是目前大气中痕量气体柱浓度高精度遥测的一种重要方法.本研究基于地基高分辨率傅里叶变换红外光谱仪采集的近红外太阳吸收光谱反演出大气中CO_2的稳定同位素~(13)CO_2和~(12)CO_2.在选择的~(13)CO_2的三个光谱窗口和~(12)CO_2的两个光谱窗口光谱拟合残差都很小,光谱拟合质量高.实验观测期间CO_2同位素~(13)CO_2和~(12)CO_2的反演误差平均值分别为(1.18±0.27)%和(0.89±0.25)%;利用Allan方差计算出观测系统的碳同位素比值δ~(13)C的测量精度为0.041‰.获得了2015年9月18日至2016年9月24日一年内大气中碳同位素比值δ~(13)C的长时间序列.结果表明,在整个测量期间δ~(13)C在-7.58‰--11.66‰范围内变化,平均值为(-9.5±0.57)‰;δ~(13)C有着明显的季节变化,冬季最小,夏季最大.分析了取暖导致的化石燃料燃烧排放增多是冬季大气中CO_2重同位素~(13)CO_2贫化的原因.观测结果显示了高分辨率傅里叶变换红外光谱仪具有准确和高精度观测大气中CO_2的稳定同位素和同位素比值δ~(13)C的能力.     

Development of a compact quantum cascade laser spectrometer for field measurements of CO2 isotopes

We report the development of a field-deployable, pulsed quantum cascade laser spectrometer. The instrument is designed to measure the ¹³C/¹²C isotopic ratio in the CO₂ released from volcanic vents. Specific ¹²CO₂ and ¹³CO₂ absorption lines were selected around 4.3 m, where the P-branch of ¹²CO₂ overlaps the R-branch of ¹³CO₂ of the 00⁰1–00⁰0 vibrational transition. This particular selection makes the instrument insensitive to temperature variations. A dual-channel cell balances the two absorption signals. We provide details of the instrument design and a preliminary demonstration of its performance based on laboratory measurements of ¹⁶O¹²C¹⁶O and ¹⁶O¹²C¹⁸O. PACS 42.55.Px; 42.62.Fi; 07.88.+y     

Voigt line infrared atmospheric transmittance calculations by Fourier transform

The absorption coefficient space of an i.r. atmospheric path contains the linear superposition of many Voigt spectral lines. This paper discusses the practical application of Karp's method to the simulation of satellite transmittance and radiance observations by using fast Fourier transforms on the recursively generated Voigt transforms. Although the procedure is physically straightforward, it is nonetheless computationally demanding and suited primarily to narrow isolated Q-branch regions. Performing the calculation on a 2.4 cm^-1 wide 15 μ CO₂Q-branch region demonstrates that 4% of the total absorption takes place above 0.1 mb. This absorption is in the cold mesopause and results in a 1–2% radiation deficit with its inclusion in a satellite radiation calculation.     

Remote measurement of volcanic gases by Fourier transform infrared spectroscopy

Received: 25 March 1998     

Field measurements of volcanic gases using tunable diode laser based mid-infrared and Fourier transform infrared spectrometers

The first field measurements of volcanic gases using mid-IR difference frequency laser spectroscopy are reported. The results were obtained at the summit crater of Masaya volcano, Nicaragua, with the gases being drawn into a multi-pass cell and measured at reduced pressure. Automated sensitive and selective detection of CO₂, SO₂, H^35,37Cl, H₂O, and CH₄ was achieved. Simultaneous measurements obtained with open-path Fourier transform spectroscopy provide a useful comparison of the two optical techniques. We also consider the potential measurement of CO₂ isotopic ratios in volcanic gases using laser-based spectroscopy.     

全蝎不同部位的红外光谱分析与评价

采用傅里叶变换红外光谱及其二阶导数谱对动物药全蝎由表及里8个部位的药材粉末进行了分析与评价.结果表明,全蝎不同部位的红外光谱较为相似,而二阶导数红外光谱中峰位置和峰强度的差异明显.全蝎不同部位的分析结果进一步证明:蛋白质是每个部位的主体成分,但蝎尾的蛋白质与其他部位较为不同;脂肪类物质主要集中于躯干部分;硫酸粘多糖普遍...     

基于傅里叶变换红外光谱和聚类分析的真菌鉴别

傅里叶变换衰减全反射红外光谱法(FTIR-ATR)应用于微生物的快速鉴定及分类是近几年发展起来的一门新型技术。该文应用FTIR-ATR光谱法与聚类分析方法相结合对重要的植物病原真菌进行鉴别。在PDA玻璃纸平板上培养了来自14个属的17株真菌,用FTIR-ATR光谱法测其红外光谱,获得了分辨率高、重现性好的真菌红外谱图,分析主要吸收峰的归属,确定了1800～1485,1485～1185与1185～900cm-1三个分析灵敏区,并在此基础上进行了系统聚类分析,使所有测试菌株都得到正确归类。结果表明,傅里叶变换红外光谱技术具有快速、准确、易操作等优点,将成为微生物研究领域的一个重要工具。     

Fourier transform infrared emission spectra of MnH and MnD

Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X⁷Σ⁺ electronic state. The vibration-rotation bands from v = 1 → 0 to v = 3 → 2 for MnH and from v = 1 → 0 to v = 4 → 3 for MnD were recorded at an instrumental resolution of 0.0085 cm⁻¹. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant (ω_e) for MnH was found to be 1546.84518(65) cm⁻¹, the equilibrium rotational constant (B_e) is 5.6856789(103) cm⁻¹ and the eqilibrium bond distance (r_e) was determined to be 1.7308601(47) Å.     

Spectroscopic investigations on kidney stones using Fourier transform infrared and X‐ray fluorescence spectrometry

Kidney stone is the most painful and prevalent urological disorder of the urinary system throughout the world. Thus, analysis of kidney stones is an integral part in the evaluation of patents having stone disease. Spectroscopic investigations of stones provide an idea about the pathogenesis of stones for its better cure and treatment. Hence, the present work targets multispectroscopic investigations on kidney stones using Fourier transform infrared (FTIR) and wave dispersive X‐ray fluorescence (WD‐XRF) spectroscopy which are the most useful analytical methods for the purpose of bio‐medical diagnostics. In the present study, FTIR spectral method is used to investigate the chemical composition and classification of kidney stones. The multicomponents of kidney stones such as calcium oxalate, hydroxyl apatite, phosphates, carbonates, and struvite were investigated and studied. Qualitative and quantitative determination of major and trace elements present in the kidney stones was performed employing WD‐XRF spectroscopy. The wide range of elements determined in the kidney stones were calcium (Ca), magnesium (Mg), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl), sulfur (S), silicon (Si), iodine (I), titanium (Ti), iron (Fe), ruthenium (Ru), zinc (Zn), aluminum (Al), strontium (Sr), nickel (Ni), copper (Cu), and bromine (Br). For the first time, ruthenium was detected in kidney stone samples employing WD‐XRF in very low concentration. Our results revealed that the presence and relative concentrations of trace elements in different kinds of stones are different and depend on the stone types. From the experiments carried out on kidney stones for trace elemental detection, it was found that WD‐XRF is a robust analytical tool that can be useful for the diagnosis of urological disorders. We have also compared our findings with the results reported using XRF technique. The results obtained in the present paper show interesting prospects for FTIR and WD‐XRF spectrometry in nephrolithiasis. Copyright © 2017 John Wiley & Sons, Ltd.