Ultrasonic preparation of tetraoxalyl ethylenediamine melamine resin-coated multiwalled carbon nanotubes for trace Ni(II) sensing

Under an aid of ultrasonic, tetraoxalyl ethylenediamine melamine resin-coated multiwalled carbon nanotubes were prepared for Ni(II) sensing in aqueous solution. The processes involved the fabrication of tetraoxalyl ethylenediamine melamine resin by one pot way, the coating of tetraoxalyl ethylenediamine melamine resin at multiwalled carbon nanotubes (MWCNTs), and the determination of Ni(II). The present materials were carefully examined by Fourier transform infrared spectroscopy, field emission scanning electron microscope, and electrochemistry techniques. A great deal of amorphous microsphere could be observed for tetraoxalyl ethylenediamine melamine resin with an average diameter of 1.2 μm, and MTE could evenly adhere at the surface of MWCNTs by the ultrasonic. Tetraoxalyl ethylenediamine melamine resin-coated multiwalled carbon nanotube-modified paraffin-impregnated graphite electrode was successfully used for the determination of Ni(II) by differential pulse adsorptive anodic stripping voltammetry. The current responses (?0.3 V) were linearly increased depending on the concentration from 1?×?10^?11 to 3?×?10^?10 M (i (μA)?=?11.1?+?7.9 c (1?×?10^?12 M); R?=?0.9901, 3σ?=?7?×?10^?12 M).     

A Novel Measurement Method of the Emission Rules of Greenhouse Gases from Fertilized Soil Based on Fourier Transform Infrared Spectrometry with Long Optical Path

Farm soil is the main source of greenhouse gas emission. We developed an optical system for measuring nitrous oxide and carbon dioxide from soil using infrared spectrometer and long optical path gas cell based on multi-reflecting mirrors. The spectral characteristics of nitrous oxide at 2198–2223 cm^?1 and of carbon dioxide at 2258–2283 cm^?1 were observed with the system. We studied the rules of greenhouse gas emission and found that nitrous oxide increased with soil moisture whereas carbon dioxide showed no obvious relationship with moisture. We also studied the diurnal variation rules of nitrous oxide and carbon dioxide from fertilized soil. These results are consistent to the previous results obtained with other analytical methods. The results indicate that the infrared spectroscopy with long optical path is an effective way to measure greenhouse gas emission from soil.     

Intumescent Flame Retardancy and Thermal Degradation of Epoxy Resin Filled with Ammonium Polyphosphate Using Thermogravimetric Analysis–Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis–Mass Spectrometry

The flammability of epoxy resin (EP) and its composite with ammonium polyphosphate (EPAPP) was investigated with limiting oxygen index (LOI), UL 94, and cone calorimeter tests. A systematic and comparative evaluation of the thermal degradation of EP and EPAPP has been investigated using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) and thermogravimetry coupled with mass spectrometry (TG–MS). The results showed that the flame retardant of ammonium polyphosphate (APP) can constitute an intumescent flame retardant (IFR) system with EP, and APP can effectively improve the LOI of EP; with 6 wt% addition level of APP, EPAPP can pass UL 94 V 0 test. The cone calorimeter test results showed that the flame retardancy and smoke suppression of EP were significantly improved by APP, and toxic gas products such as carbon monoxide and carbon dioxide obviously decreased. Thermogravimetry–Fourier transform infrared spectroscopy and TG–MS results showed that the degradation process of EP produces large amounts of gas products and mainly containing of water, carbon dioxide, methane, benzene and its derivatives, as well as phenol and its derivatives. Compared to EP, the kinds of decomposition products of EPAPP sample were not changed significantly, except that more ammonia gas was generated. For the EPAPP sample, the products of water, benzene, and phenol increased, whereas the carbon dioxide and the flammable hydrocarbon fragments C_xH_y decreased significantly during the decomposition.     

利用TG-FTIR联用技术对Kevlar纤维的热解过程的分析

现代工业应用与技术领域要求材料具有良好的机械性质与热学性质,Kevlar纤维做为近年来材料领域研究的热点纤维材料,具有高强度、耐高温等良好的性能。纤维材料的性质依赖于自身的结构和组成,热分解过程对于研究材料的结构和热学性质有着十分重要的意义。热红联用技术做为一种新型的联用技术,既能定量又能定性地进行分析,在研究材料的热分解过程中具有明显的优势。由于Kevlar纤维的热分解过程在文献中少有报道,本文首次利用TG-FTIR联用技术对Kevlar纤维在室温到800 ℃的热解过程进行分析,得到了Kevlar纤维热解过程的详细步骤及各个步骤的反应产物。结果表明,Kevlar纤维的热解经历了3个阶段,分别为100～240,240～420,420～800 ℃。在500 ℃之前Kevlar纤维失重很缓慢,第三个阶段是纤维的主要失重阶段,最终固体的残留质量为56.21%。红外光谱数据表明,Kevlar纤维热解过程先释放出游离水,随后发生脱水反应和解聚反应,使纤维分子链断裂。最后纤维碎片进一步反应生成小分子气体,水、氨气、一氧化碳、二氧化碳为主要产物。其中水的析出量逐渐增大;氨气的析出量保持基本一致;一氧化碳仅在515～630 ℃产生,随后即氧化生成二氧化碳;二氧化碳的析出量经历了一个由于一氧化碳转化而产生的增长后,又下降到一定值保持稳定。     

基于傅里叶变换红外光谱法CO2气体碳同位素比检测研究

介绍了基于傅里叶变换红外技术检测CO₂气体碳同位素比的新方法, 详细介绍了如何从HITRAN红外数据库中提取气体标准吸收截面; 介绍了基于非线性最小二乘法反演CO₂气体碳同位素比和整套实验装置的组成及实验步骤. 从理论和实验分析两方面讨论了温度和气压变化对δ¹³CO₂值的影响规律. 对于同一CO₂标准气体, 采用FTIR和同位素质谱法两种技术进行了δ¹³CO₂值对比检测, 两种测量技术的平均值差异仅为0.25%. 从实验结果可以看出, FTIR技术可以实现对CO₂气体碳同位素比的检测.     

17O12C17O and 18O12C17O spectroscopy in the 1.6 μm region

Near infrared spectra of a carbon dioxide sample enriched with oxygen-17 have been recorded using a high-resolution continuous scan Fourier transform interferometer fitted with a femto OPO/Idler laser source. Cavity enhanced absorption has been achieved in a static gas cell allowing an optimal rms noise equivalent absorption of 1.2?×?10^?10?cm^?1?Hz^?1/2 per spectral element to be reached, corresponding to α_min?=?10^?8?cm^?1. Spectra were calibrated against acetylene reference line positions. Three bands in the 3ν₁?+?ν₃ tetrad in both ¹²C¹⁷O₂ and ¹²C¹⁷O¹⁸O have been identified and rotationally analyzed, as well as some related hot bands, eight of which are newly reported and three with their analysis updated compared with a preliminary report (X. de Ghellinck d’Elseghem Vaernewijck et al., Chem. Phys. Lett. 514, 29 (2011)).     

Reflection-absorption infrared and thermal desorption studies of carbon monoxide and hydrogen adsorbed on rhodium

Reflection-absorption infrared spectroscopic and thermal desorption techniques have been used to study the interaction of mixtures of carbon monoxide and hydrogen with evaporated rhodium films. For equimolar mixtures near 10^?9 Torr, hydrogen adsorbed much more rapidly, but long exposure times or increases in CO pressures to 10^?6 Torr led to its partial, but never complete, displacement by adsorbed carbon monoxide. Hydrogen desorption spectra taken during the displacement process showed two peaks which was consistent with a cooperative interaction between adsorbed CO and H species. In contrast to previous transmission studies of CO adsorption on small rhodium particles, the present reflection—absorption infrared study of the film system showed a single absorption band at 2075 ±10 cm^?1. While explanations for the discrepancy in terms of particle size effects are possible it is considered more likely that all CO molecules are linearly bound to individual Rh atoms in the present situation. In our work, increases in CO pressure (especially above 10^?6 Torr) were accompanied by an upward frequency shift (from 2065 cm^?1 to 2085 cm^?1) and a narrowing in half width (from 25 to 17 cm^?1). Several possible explanations for the latter unusual effect are discussed.     

Photoacoustic monitoring of gases using a novel laser source tunable around 2.5 μm

We present the first spectroscopic measurements using a tunable solid state Cr²+:ZnSe laser emitting at wavelengths between 2.2 μm and 2.8 μm. Photoacoustic measurements on various gases such as methane, carbon monoxide, carbon dioxide, water vapour, nitrous oxide, and ambient air were carried out. In this paper, we present measurements on methane, nitrous oxide, and ambient air. The deduced detection limits are in the low ppm or sub-ppm range, e.g., 0.2 ppm for carbon dioxide, 0.8 ppm for methane and 2.7 ppm for carbon monoxide.     

Effect of 50 MeV Li+3 and 80 MeV C+5 ions’ beam irradiation on the optical,structural, chemical and surface topographic properties of PMMA films*

The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50?MeV lithium (Li³⁺) and 80?MeV carbon (C⁵⁺) ions to the fluences of 3?×?10¹⁴, 1?×?10¹⁵, 1?×?10¹⁶ and 1?×?10¹⁷ ions µm^?2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet–visible (UV–Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV–Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. E_g and E_a decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (E_g) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.     

Nitrogen-broadened halfwidths of HF lines in the 1-0 band

Nitrogen-broadened halfwidths for seven lines in the fundamental infrared band of HF have been determined from laboratory measurements at room temperature. The spectra were recorded using a Fourier transform spectrometer with a nominal resolution of 0.0603 cm^?1. A nonlinear least-squares spectral-fitting technique was used in the data analysis to obtain halfwidth values for the P3 through R3 lines, with an average uncertainty of approximately 15%.     

Tunable diode laser measurement of pressure-induced shift coefficients of CO2 around 2.05 μm for Lidar application

Atmospheric carbon dioxide (CO₂) is one of the main contributors to the greenhouse effect. A global monitoring of CO₂ from space is foreseen as a key issue to quantify its sources and sinks at a regional scale and to better predict future levels of CO₂ and their effect on climate change. Differential Absorption Lidar (DiAL) is a promising and novel spectroscopic technique for remote sensing CO₂ spatial and temporal concentration distribution with a high level of accuracy. However, a precise knowledge of spectroscopic parameters of CO₂ molecular transitions and their dependence with temperature and pressure is required for reducing the uncertainty on DiAl measurements. Hence, to support remote sensing of carbon dioxide in the troposphere, we report on the accurate determination of air pressure-induced shift coefficients for eight absorption lines belonging to the R branch of (20⁰1)_III←(00⁰0)_I band of CO₂ at 2.05 μm. Purposely, a high-resolution tunable diode laser absorption spectrometer (TDLAS) coupled to a cryogenically cooled optical cell was implemented. From these measurements, we have further determined the temperature-dependencies of the air pressure-induced shift coefficients.     

Simultaneous sensing of temperature,CO, and CO2 in a scramjet combustor using quantum cascade laser absorption spectroscopy

A mid-infrared laser absorption sensor was developed for gas temperature and carbon oxide (CO, CO₂) concentrations in high-enthalpy, hydrocarbon combustion flows. This diagnostic enables non-intrusive, in situ measurements in harsh environments produced by hypersonic propulsion ground test facilities. The sensing system utilizes tunable quantum cascade lasers capable of probing the fundamental mid-infrared absorption bands of CO and CO₂ in the 4–5 µm wavelength domain. A scanned-wavelength direct absorption technique was employed with two lasers, one dedicated to each species, free-space fiber-coupled using a bifurcated hollow-core fiber for remote light delivery on a single line of sight. Scanned-wavelength modulation spectroscopy with second-harmonic detection was utilized to extend the dynamic range of the CO measurement. The diagnostic was field-tested on a direct-connect scramjet combustor for ethylene–air combustion. Simultaneous, laser-based measurements of carbon monoxide and carbon dioxide provide a basis for evaluating combustion completion or efficiency with temporal and spatial resolution in practical hydrocarbon-fueled engines.     

UV Fourier transform absorption cross sections of benzene,toluene, meta-, ortho-, and para-xylene

New measurements of the absorption cross sections of gaseous benzene, toluene, meta-, ortho-, and para-xylene have been performed with a Fourier transform spectrometer Bruker IFS120 M at the resolution of 1 cm^?1 over the 30 000–42 000 cm^?1 spectral range. The recordings were carried out under different pressure and temperature conditions with pure samples. The effect of the temperature on the absorption cross sections is investigated. Comparison with the literature shows large differences, largely attributed to the experimental difficulties encountered during these previous measurements and to a resolution effect. To our knowledge, it is the first time that such a dataset of UV absorption cross sections with temperature dependence is reported in the literature. Such data should be useful for upcoming remote sensing applications, such as atmospheric studies both on Earth and on other planets.     

Broadly tunable quantum cascade laser in cantilever-enhanced photoacoustic infrared spectroscopy of solids

An external cavity quantum cascade laser (EC-QCL) is applied in the photoacoustic detection of solid samples. The EC-QCL used has a broad tuning range of 676 cm^?1 (970–1,646 cm^?1) in the mid-infrared region, which enables accurate broadband spectroscopy of large molecules. The high spectral power density of the EC-QCL is combined with an extremely sensitive optical cantilever microphone of the photoacoustic detector to achieve an ultimate sensitivity. The carbon black, polyethylene, and hair fiber samples were measured with the EC-QCL photoacoustic detection using electrical amplitude modulation to demonstrate the possibilities of the setup. The same measurements were repeated with a Fourier transform infrared (FTIR) spectrometer combined with a photoacoustic detector for a comparison. The EC-QCL photoacoustic setup yielded roughly a decade better signal-to-noise ratios than the FTIR setup with the same measurement time.     

Study on Infrared Spectral Radiance by Remote Fourier Transform Infrared Spectroscopy

Abstract

Infrared emission spectra emitted by high luminosity infrared pyrotechnics have been observed remotely using the Fourier transform infrared spectroscopy. The primary purpose of the study is to determine infrared spectral radiance distribution, their time—resolved spectra and integrated emission energy. The spectra have been recorded between 4000 – 800cm^?1 region with spectral resolution of 4cm^?1. The study is very important for many applications.     

Carbon monoxide and carbon dioxide interaction with tantalum

The adsorption of carbon monoxide and carbon dioxide on tantalum and the dissolution of these gases in the adsorbent at T ? 300 K have been studied. The flash-filament method (FFM) in a monopole mass-spectrometer and a field emission microscopy was used in the same apparatus. Carbon monoxide and carbon dioxide dissociate on the tantalum surface, carbon monoxide being desorbed in both cases during the flash. The desorption curves of CO reveal three different binding states: two of them (α and $\text{}\text{?}$gb₁) for the adsorbed particles whereas the high temperature desorption state relates to the adsorbate dissolved in the metal, For the $\text{}\text{?}$gb₁ state of CO the activation energy, the pre-exponential factor and the kinetic order in the kinetic equation of desorption have been estimated. They turned out to be E = 110 kcal/mol, C = 3 × 10¹²sec^?1, and ν = 1. The activation energy of diffusion for CO in tantalum and the energy of outgassing for the metal were found to be 9.4 and 49 kcal/mole, respectively.     

CO2及其碳同位素比值高精度检测研究

改进了一种基于傅里叶变换红外光谱法测量CO₂气体的装置, 改进后的装置能够提高CO₂检测精度, 并能同时测量CO₂碳同位素比值. 研究了温度和压力对CO₂浓度值和CO₂碳同位素比值测量的影响规律. 利用该装置连续测量了标准CO₂气体和环境大气, 对标准CO₂气体测量得到的CO₂浓度值及其碳同位素比值进行温度和压力影响修正, 获得了较好的精度和准确度. 关键词： 光谱学 同位素比值 傅里叶变换红外光谱 二氧化碳     

直射太阳光红外吸收光谱技术遥测大气中二氧化碳柱浓度

大气中二氧化碳浓度持续增高导致环境和气候变化等问题成为人们关注的焦点. 为了实时遥测二氧化碳气体柱浓度, 研究了一种地基低分辨遥测系统和实时光谱数据反演分析方法. 利用该系统在合肥地区进行了连续观测, 从太阳吸收光谱中实时获取了整层大气透过率. 采用逐线积分非线性最小二乘光谱反演算法, 从整层大气透过率中反演了二氧化碳柱浓度和氧气柱浓度, 并以氧气柱浓度为内标函数获得了二氧化碳干空气柱体积混合比, 精密度优于3%. 将2012年9月25日12时到15时本系统测量的二氧化碳干空气柱体积混合比均值与此时段过境本站点区域的日本温室气体卫星观测结果进行了比较, 两者偏差小于1%.可见, 该系统和方法具有很高的精密度和准确度, 是一种有效的温室气体观测手段. 关键词： 红外吸收光谱技术 遥测 二氧化碳 柱浓度     

High-resolution infrared and laser photoacoustic spectroscopy of monochloroacetylene

High-resolution vibration—rotation spectra of monochloroacetylene (HCCCl) have been recorded in two different wavenumber regions. Fourier transform infrared interferometer measurements in the 4000–10000cm^?1 range have been performed with a resolution of 0.005–0.016cm^?1 and titanium: sapphire ring laser intracavity photoacoustic measurements in the 12500–12600cm^?1 and 12800–12860cm^?1 regions have been carried out with a Doppler-limited resolution of about 0.02 cm^?1. Altogether, 40 vibrational bands belonging to the HCC³⁵ Cl and 15 bands belonging to the HCC³⁷ Cl isotopic species have been rotationally assigned. A vibrational model, based on the conventional rectilinear normal coordinate theory including anharmonic Fermi, Darling—Dennison and vibrational l-type doubling resonances, has been used to attach vibrational labels to the bands. This approach is found to describe well the rovibrational energy level structure at least in the energy range covered in this work. The model shows that the CH oscillator becomes decoupled from the rest of the molecule as vibrational energy increases.     

Sulfur/mesoporous carbon composites combined with γ-MnS as cathode materials for lithium/sulfur batteries

With the aim to develop high-performance sulfur electrode, manganese sulfide (MnS) was combined with sulfur/porous carbon composite electrode by a simple precipitation method. Both X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results show that as-prepared MnS corresponds to Rambergite phase with a hexagonal structure (γ-MnS). MnS could be uniformly dispersed in the carbon matrix when the content was less than 20 wt%. When the content of MnS increased, γ-MnS particles aggregated on both outside of the mesoporous carbon channels and the surface of carbon particles. The CV curves of MnS/MC in the first cycle were similar to elemental sulfur, indicating partially decomposed MnS at the surface of mesoporous carbon. Charge/discharge tests indicated that the initial discharge-specific capacity of S/MnS/MC was 1412.5 mAh g^?1 and remained a reversible capacity of 727.4 mAh g^?1 after 50 cycles at a current of 100 mA g^?1, which is superior to that of sulfur composite electrode without MnS.