乙二醛在沙尘颗粒物表面吸附与转化的红外光谱研究

乙二醛是大气中一种重要挥发性有机物.它在大气中气相、水相及二次无机酸性颗粒物表面反应均可生成二次有机气溶胶(SOA).然而乙二醛与沙尘非均相反应研究却未见报道.本研究选取二氧化硅(SiO2)和三氧化二铝(α-Al2O3)颗粒作为实际沙尘模型,探讨了乙二醛与沙尘颗粒非均相吸附与转化机理.利用透射傅里叶变换红外光谱(T-FTIR)原位跟踪反应进程,再结合色谱和质谱分析了反应产物.结果发现,在无光照和无氧化剂参与条件下,乙二醛在以上两种沙尘组分颗粒表面吸附后均生成了低聚物,在α-Al2O3上还能生成有机酸；水汽能促进颗粒对乙二醛摄取,并有利于低聚物生成,但会抑制有机酸生成.这些发现对于认识大气乙二醛与沙尘非均相反应生成SOA具有重要意义.     

SO2在CaCO3颗粒表面转化的DRIFTS研究

碳酸钙 (CaCO3 )是大气中矿物颗粒物的重要组分 ,其非均相大气化学行为很不清楚。利用原位漫反射红外傅里叶变换光谱 (DiffuseReflectanceInfraredFourierTransformSpectroscopy ,DRIFTS)研究了二氧化硫(SO2 )在CaCO3 颗粒物表面的转化情况。通过比较不同条件下 ,亚硫酸盐和硫酸盐的原位光谱 ,探讨了SO2在CaCO3 表面氧化中臭氧 (O3 )所起的作用。结果表明 ,利用DRIFTS原位分析反应器研究CaCO3 表面硫酸盐的生成是可行的。在存在O3 条件下 ,SO2 在CaCO3 表面能够被氧化成硫酸盐 ,反应分为吸附和氧化两个步骤进行。     

SO_2与过渡金属离子在Soot上的非均相反应

应用FTIR-ATR研究了过渡金属离子与SO_2在Soot颗粒物表面的非均相反应,研究了在不同相对湿度(RH)环境且有Fe~(3+)和Mn2+存在条件下,SO_2在Soot颗粒表面发生的非均相反应过程。发现Fe~(3+)和Mn2+对于SO_2的非均相氧化反应有着显著的催化效应,并且随着RH的增加,硫酸盐的生成速率逐渐增大。该研究加深了对SO_2的迁移转化规律及其致霾效应的理解。     

碳酸钙粒径对SO_2非均相反应的影响研究

利用DRIFTS研究了SO_2在CaCO_3颗粒物表面O_3氧化的非均相反应,对常温(298K)且干燥条件下(相对湿度1%)CaCO_3粒径对SO_2非均相反应的影响做了初步探究。研究结果表明,在相同反应时间里,生成的硫酸盐的红外积分面积随粒径增加而降低,说明碳酸钙粒径越小,越有利于生成硫酸盐。     

红外显微化学图像技术在空心微球制备中的应用

在考察聚苯乙烯(PS)与聚乙烯基苄氯(PVBCl)相容性及干涉效应对测量结果影响的基础上,使用红外显微化学图像技术研究表征了PS与PVBCl混合物薄膜和微球的相分离情况,对比分析了不同处理条件下制备的微球半球壳中两种聚合物的相分离红外显微化学图像。研究结果表明建立的研究方法可以用来定性或半定量的分析球壳内PS和PVBCl两聚合物的分相情况,在测试中样品的干涉效应会对测量造成较大的不确定度,在不同温度下获得的聚合物微球样品中,40℃条件下两聚合物的分相情况更为理想。该研究为探索非均相双半球型聚合物微球制备条件以及红外显微化学图像法表征聚合物相分离提供了一种直观可行的表征方法,但受空间分辨率的影响,该方法不适合于6.25μm×6.25μm以下尺寸样品的分析。     

有机种子对异戊二烯光氧化反应形成二次有机气溶胶的粒谱演化和形成速率的影响

基于室内烟雾箱实验平台,研究了在有机种子气溶胶下,来自OH启动异戊二烯光氧化反应形成的二次有机气溶胶的动力学. 探究了二次有机气溶胶的粒谱分布分别与来自室内大气中痕量碳氢化合物光氧化反应产生的种子颗粒物浓度以及前体物异戊二烯浓度的依赖关系. 研究结果表明在高浓度种子气溶胶和低浓度异戊二烯条件下(对应于典型城市大气条件),光化学反应形成的二次有机产物凝聚到种子颗粒物表面而造成的颗粒物增长起主导作用;而在低浓度种子气溶胶和相对高浓度异戊二烯条件下(对应于典型偏远地区大气条件),二次有机气溶胶粒谱分布出现双模式结构,分别对应于来自均相成核的新粒子生成和二次有机产物在种子颗粒物上的凝聚增长. 此外,还研究了有机种子颗粒物浓度对二次有机气溶胶形成的影响,评估了在不同种子浓度下二次有机气溶胶粒谱分布的演化和相应新粒子的形成速率.     

原位红外光谱法研究大气颗粒物表面非均相反应

大气污染物之间可能发生协同作用,造成严重的二次污染,产生次生环境问题.本实验通过原位红外光谱分析方法研究气态污染物和碳颗粒物之间的吸附过程,发现大气中CO2和NO极易在颗粒物表面发生吸附;CO2在颗粒物表面达到吸附平衡时间很短,NO的吸附平衡时间较长;CO2和SO2会影响NO在颗粒物表面的吸附,CO2在颗粒物表面的吸附几乎不受NO和SO2的影响.     

红外光谱研究氯化钠-马来酸单液滴反应

大气颗粒物中无机盐和有机酸之间的化学作用是近年来的研究热点。利用傅里叶变换显微红外(micro-FTIR)光谱手段探究了氯化钠和马来酸混合单液滴在不同湿度下的反应,结果发现,HCl气体的挥发促进了反应的进行。     

光镊-受激拉曼光谱技术测量SO2与悬浮NaCl单液滴的氧化反应动力学速率常数

硫酸盐是大气雾霾颗粒中一种重要的二次无机组分,但是有关大气硫酸盐生成机制的认识,目前还存在很多不足。同时,现有的空气质量模型也往往存在对硫酸盐生成量的低估问题,无法有效复现外场观测结果。因此,深入研究大气硫酸盐的生成机制,对理解雾霾成因、实现大气污染的精准防控具有重要意义。本研究利用光镊-受激拉曼光谱技术观测了SO_2与NaCl液滴的非催化氧化反应过程,液滴半径在反应过程中的纳米级变化可被精确测量,实现了反应过程的实时、原位观测。根据测定的反应速率,求算了SO_2氧化过程的拟一级反应速率常数k,同时研究了相对湿度、SO_2浓度对反应的影响。结果表明,相对湿度变化引起的液滴离子强度变化对k值具有显著影响,湿度由～60%增加至～90%时,k值下降约1个数量级。而SO_2浓度提升会使得液滴pH减小,导致k略微下降。对反应过程的机制讨论表明,SO_2在NaCl液滴中的非催化氧化过程体相反应、界面反应可能均有贡献。     

获取大气颗粒物消光系数的差分吸收光谱法研究

针对雾霾天气日益增多,大气污染气体向颗粒物的转化在加快,研究了一种大范围对其监测的差分吸收光谱方法。差分吸收光谱法可以实时、在线、准确同时获取颗粒物光学特性和大气痕量气体浓度。论文首先分析了双光路差分吸收光学遥感系统获取颗粒物绝对光强的原理,然后研究了基于单光路测量大气吸收谱,在干净天气状况下测量参考光谱,利用能见度数据,在550 nm波段处实现系统校准,计算校准参数,从而获得大气绝对吸收光强,然后解析出大气总的消光系数。再从总的大气消光系数中,去除瑞利散射以及大气痕量气体吸收对消光系数影响后,精确解析出颗粒物消光系数。同时基于差分思想获取大气痕量气体的浓度。最后把该方法应用于外场实验,获取大气颗粒物在350～700 nm波段范围内消光系数和大气中NO₂的浓度。研究结果表明颗粒物消光系数的随着波长的增加而减少,符合Angstrom公式。该研究为分析大气气相/粒子非均相化学反应提供有力的技术支持。     

Application of Fourier Transform Infrared Spectroscopy in the Study of Atmospheric Heterogeneous Processes

Abstract

Atmospheric heterogeneous processes associated with the complex behavior of atmospheric particles may play a crucial role in atmospheric chemistry and global climate change. Many of these heterogeneous processes have been widely investigated in detail over the years, including heterogeneous reactions on the surface of aerosol particles, aerosol hygroscopicity, as well as aerosol chemical compositions. As a fast, sensitive, precise, nondestructive, in situ, and online experimental technique, Fourier transform infrared (FTIR) spectroscopy has played a significant role in investigating atmospheric heterogeneous processes. On the basis of the mechanisms and characteristics of various FTIR techniques, this work presents a review of the applications of in situ FTIR spectroscopy in atmospheric heterogeneous processes study, and future development directions for FTIR spectroscopy are proposed considering current and future research needs for heterogeneous processes.     

Studies of Atmospherically Relevant Reactions Using Differentially Pumped Mass Spectrometer and Fourier Transform Infrared Spectroscopy

This article describes recent studies of atmospherically relevant reactions using spectroscopic techniques by our group at the Wadsworth Center. Heterogeneous reactions of SO₂ with either HOBr or HOCl on ice have been studied using a coated-wall flow reactor coupled with differentially pumped quadrupole mass spectrometer, and the reaction of NO₂+HI has been investigated using Fourier transform infrared spectroscopy (FTIR). Reaction probabilities or rate constants have been determined at relevant atmospheric temperatures. Specular reflection-absorption infrared spectroscopy and the temperature programmed desorption technique were employed to study the adsorption of oxalic acid on a Cu surface at 175 K. Reflection-absorption infrared spectroscopy showed that oxalic acid is molecularly adsorbed on the Cu surface. The results obtained from these studies provide a better understanding of atmospheric reactions at a molecular level and enable an assessment of the relative importance of the reactions in the atmosphere.     

Application of Fourier Transform Infrared Spectrophotometry in Pharmaceutical Drugs Analysis

This review provides some background to infrared spectroscopy including Fourier transform infrared spectroscopy. It is not meant to be complete or exhaustive but to provide the reader with sufficient background for selected applications in pharmaceutical analysis. Fourier transform infrared spectroscopy (FTIR) is a fast and nondestructive analytical method. Associated with chemometrics, it can become a powerful tool for the pharmaceutical industry. Indeed, it is suitable for analysis of solid, liquid, and biotechnological pharmaceutical forms. This review focuses on pharmaceutical FTIR applications used for qualitative and quantitative analysis. Moreover, it can be implemented during pharmaceutical development, in production for process monitoring, and in quality control laboratories.     

机载FTIR地球大气红外背景辐射光谱特征研究

介绍了机载傅里叶变换红外(FTIR)光谱仪测量地球大气红外背景辐射的实验过程,对地球/大气的红外背景辐射进行了详细的分析,给出了描述这一辐射过程的理论表达式,证明红外背景辐射主要取决于地表温度、地表发射率、大气透过率和大气温度这四个参数。在理论分析的基础上,对不同观测高度、不同地物背景的实测光谱进行了对比和分析,得到了红外背景辐射的光谱特征。     

PSⅡ中蛋白二级结构中β聚合效应的红外光谱研究

利用Fourier变换红外光谱（FTIR）方法研究了光系统Ⅱ（PSⅡ）膜颗粒中蛋白二级结构在高温条件下的β聚合效应。具有生物活性和高温蛋白的β聚合样品的红外光谱测量温度均是室温，它们的酰胺Ⅰ吸收带被用来对两种样品的特性进行定量的分析。光谱的分析方法采用了直接Lorentz线型拟合，光谱结果表明光系统Ⅱ二级结构在400℃下发生热变性后，其红外光谱将发生很强的不可逆的变化。但其红外光谱与活性PSⅡ蛋白一样仍可用3个Lorentz线型拟合，显示了FTIR红外光谱方法在研究蛋白热变性方面的优越性。     

Recent Applications of Fourier Transform Infrared Spectrophotometry in Herbal Medicine Analysis

Abstract

Fourier transform infrared spectroscopy (FTIR) is a fast and nondestructive analytical method. Associated with chemometrics, it is a powerful tool for the pharmaceutical industry. It is becoming a suitable technique for analysis of herbal medicine. This review focuses on the recent developments and updates for the qualitative and quantitative analysis of herbal medicine using FTIR. Moreover, it can be implemented during herbal drug development, in production for process monitoring, or in quality control laboratories.     

超分散剂在莠去津颗粒表面吸附的红外和拉曼光谱学研究

聚羧酸型梳状共聚物超分散剂在农药环保剂型悬浮剂的研究中起着重要的作用,可使其理化稳定件得到明显改善,因此研究聚羧酸型梳状共聚物超分散剂在莠去津颗粒表『疗i的吸附行为具有重要的理论和实际意义.利用傅里叶红外光谱(FTIR)和傅里叶拉曼光谱(FT-Raiman)对超分散剂在莠上津表面的吸附行为进行了光谱学表征,结果表明,氢...     

The Conversion of NOx in a Corona Discharge with an Electrode Material Variation

The spatial and surface chemical products and effectiveness of NO_x removal (abbreviated deNO_x) under the corona discharge action at atmospheric pressure were investigated. The influence of high-voltage electrode material on a discharge character and the heterogeneous influence of the electrode surface are also reported in the article. The qualitative analysis was performed using infrared absorption spectrometry. Special attention was paid to NO and NO₂ calibration measurements.     

Structural, optical and electromagnetic properties of aluminum-clay nanocomposites

Aluminum pillared and exchanged bentonite particles were synthesized by the ion exchange method. The characteristics of the particles were investigated by Fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDS), reflectance spectrophotometer (RS) and electromagnetic transition instrument (ETI). FTIR spectra showed a successful incorporation of Al complexes into the clay interlayer. The TGA result demonstrated an improvement in thermal stability of the Al-pillared clay compared with the untreated particles. SEM and EDX results showed the presence of aluminum aggregates on the surface of clay. It was also found that Al ions affect electromagnetic properties of the clay particles.