Infrared-Vacuum Ultraviolet Spectroscopic and Theoretical Study of Neutral Trimethylamine Dimer

Infrared-vacuum ultraviolet (IR-VUV) spectra of neutral trimethylamine dimer were measured in the 2500-3800 cm^-1 region. Quantum chemical calculations were performed to identify the structure of the low-lying isomers and to assign the observed spectral features. The bands at 2975 and 2949 cm^-1 were assigned to the antisymmetric C-H stretching and the band at 2823 cm^-1 to the symmetric C-H stretching, respectively. The 2739 cm^-1 band was due to the CH₃ bending overtone, which disappeared at low IR laser power of 1 mJ/mm². The extra band at 2773 cm^-1 could be due to Fermi resonance behavior of the light isotopologue, these are often close in energy and can strongly mix through cubic terms in the potential function. Experimental and theoretical results indicate the likely coexistence of multiple structures. The peak widths of IR spectra of neutral trimethylamine dimer are not significantly affected by the structural transformation, allowing the stretching modes to be well resolved.     

利用真空紫外脉冲场电离-光电子方法研究三氯乙烯阳离子振动光谱

The vacuum ultraviolet（VUV）pulsed field ionization-photoelectron（ PFI-PE）spectrum for trichloroethene（ClCH=CCl2）has been measured in the energy range of 76400-79650 cm-1 . The vibrational bands resolved in the VUV-PFI-PE spectrum are assigned based on ab initio vibrational frequencies and calculated Franck-Condon factors for the ionization transitions,yielding eleven vibrational frequencies for ClCH=CCl2+:v1+=148 cm-1,v2+= 80 cm-1,v3+=286 cm-1,v4+=402 cm-1,v5+= 472 cm-1,v6+=660 cm-1,v7+=875 cm-1,v8+=990 cm-1,v9+=1038 cm-1,v10+=1267 cm-1,and v11+=1408 cm-1. These measurements along with the frequency v12+=3073 cm-1 determined in the recent VUV-infrared photo-induced ionization study have provided the complete set of twelve experimental vibrational frequencies for ClCH = CCl2+ in its ground electronic state. On the basis of the spectral simulation of the origin VUV-PFI-PE vibrational band,we have determined the IE（ClCH=CCl2）to be（76441.7±2.0）cm-1（（9.4776±0.0002）eV）.     

Infrared Spectroscopy of Neutral Clusters Based on a Vacuum Ultraviolet Free Electron Laser?

Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level, but it has been proven to be a grand challenge for neutral clusters because the absence of a charge makes it difficult for the size selection and detection. Infrared (IR) spectroscopy based on threshold photoionization using a tunable vacuum ultraviolet free electron laser (VUV-FEL) has recently been developed in the lab. The IR-VUV depletion and IR+VUV enhancement spectroscopic techniques open new avenues for size-selected IR spectroscopies of a large variety of neutral clusters without confinement (i.e., an ultraviolet chromophore, a messenger tag, or a host matrix). The spectroscopic principles have been demonstrated by investigations of some neutral water clusters and some metal carbonyls. Here, the spectroscopic principles and their applications for neutral clusters are reviewed.      

Structures and Spectroscopic Properties of NaAs4 and Its Anions and Cations

The equilibrium geometries, vibrational frequencies, atomization energies, adiabatic electron separations, adiabatic detachment energies （ADE）, and adiabatic ionization potentials of the low-lying electronic states for the NaAs4 clusters and its ions were investigated employing the DFT method, and then compared with the photoelectron spectra. According to the computed results, reasonable assignments for the photoelectron spectra of NaAs4^- were suggested.     

用于紫外光谱水质分析的Boosting-偏最小二乘法

为提高水质参数总有机碳(TOC)的紫外吸收光谱分析的预测精度,提出一种基于Boosting理论的迭代式回归建模算法,并根据统计学习理论提出一种新的迭代停止判据,可有效防止过拟合,显著提高模型预测精度。为评估所提算法的性能,分别采用本算法和3种常用的光谱分析方法,即偏最小二乘、主成分回归和人工神经网络,对自行研制的紫外光谱水质分析仪实测的一组数据进行了建模和预测。计算结果表明:相对于其他3种方法,本算法具有生成的模型预测精度高的显著优势。     

Ultraviolet photolytic vapor generation from particulate ensembles for detection of malathion residues in aerosols

A method to selectively generate vapor signatures from malathion entrained within matrices of surface-impacted aerosol particles has been demonstrated. The method uses ultraviolet radiation (172 or 222 nm) from a continuous wave discharge lamp to photodissociate malathion molecules collected within and on surface-impacted particles, followed by detection via ion mobility spectrometry (IMS). Since surface heating does not occur, only those molecules whose photofragments exhibit high vapor pressure are introduced into the IMS instrument and then only those exhibiting high proton affinity are subsequently detected. This process produces less signal clutter than in pyrolysis-IMS, where the background aerosol is pyrolyzed along with the sample. Quantities of malathion as small as 50 ng could be detected when the malathion was entrained on a clean surface, and as small as 100 ng when co-entrained on a surface with much larger quantities of background aerosols such as diesel soot, road dust, Bacillus globigii, albumin, and cotton lint. This sensitivity indicates that, when combined with a particle collector as an effective pre-concentrator, detection of malathion aerosol concentrations of <0.01 mg/m³ will be possible. Since malathion can be viewed as a model compound, this technique is also extendable to the detection of organophosphate war chemicals.     

Mass Spectrometric and Photoelectron Spectroscopic Studies of Zirconium Oxide Molecular and Cluster Anions

We present a preliminary report on our mass spectrometric and photoelectron spectroscopic studies of zirconium oxide molecular and cluster anions using a newly built laser vaporization/time-of-flight/magnetic bottle, negative ion photoelectron spectrometer. This work was motivated in part by evidence which suggests that zirconium dioxide catalyzes the radiolysis of interfacial water. We present our mass spectrometric observations of oxygen-rich zirconium oxide cluster anions and our photoelectron spectra of ZrO^– and ZrO ₂ ^– . From the photoelectron spectrum of ZrO^–, the adiabatic electron affinity of ZrO was determined to be 1.3±0.3 eV, and from this value, the dissociation energy of ZrO^– (into Zr and O^–) was found to be 7.8±0.3 eV. From the photoelectron spectrum of ZrO₂, the adiabatic electron affinity of ZrO₂ was determined to be 1.8±0.4 eV.     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子能谱与电子结构研究

首次报道了N-(2-澳乙基)咔唑和N-乙烯基咏唑的气相Hel紫外光电子能谱(UPS),借助于Gaussian 94采用RHF/6-3lG基组优化几何构型,并用RHF/6-31G基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540Ve处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面.     

肉豆蔻酸和棕榈酸酸盐体系的振动光谱研究

报道了肉豆蔻酸和榈酸酸盐体系的振动光谱，结果表明，脂肪酸与其碱金属盐之间通过氢键和羧基配位形成酸盐络合物。酸盐体系中氢键具有不同于普通氢键的性质，本文结合振动光谱讨论了酸盐的结构和氢键性质。     

An Overview of the Analytical Methods for the Determination of Organic Ultraviolet Filters in Cosmetic Products and Human Samples

UV filters are a group of compounds commonly used in different cosmetic products to absorb UV radiation. They are classified into a variety of chemical groups, such as benzophenones, salicylates, benzotriazoles, cinnamates, p-aminobenzoates, triazines, camphor derivatives, etc. Different tests have shown that some of these chemicals are absorbed through the skin and metabolised or bioaccumulated. These processes can cause negative health effects, including mutagenic and cancerogenic ones. Due to the absence of official monitoring protocols, there is an increased number of analytical methods that enable the determination of those compounds in cosmetic samples to ensure user safety, as well as in biological fluids and tissues samples, to obtain more information regarding their behaviour in the human body. This review aimed to show and discuss the published studies concerning analytical methods for the determination of organic UV filters in cosmetic and biological samples. It focused on sample preparation, analytical techniques, and analytical performance (limit of detection, accuracy, and repeatability).     

氧气氛中紫外光辐照官能化HDPE的结构与性能研究

采用FT－IR，XPS，WAXD，DXC，凝胶和表面自由能力分析，研究了氧化氛中紫外辐照官能化高密度聚乙烯（HDPE）的化学结构、晶体结构和表面自由能的变化。与空气相比，在氧气氛中紫外辐照HDPE能提高C－O，C（＝O）O和C＝O等含氧基团的引入速度，同时又能降低HDPE中的凝胶含量，在空气和氧气氛中紫外辐照后，HDPE的晶型没有发生变化，仍为正交晶系；HDPE的晶胞参数a,b,c以及（110），（200），（020），（011），（111）等晶面间距基本保持不变；HDPE的熔融温度下降，但熔融热焓升高，结晶度增大，表面自由能增大，且在氧气氛中辐照HDPE的变化幅度较大。     

黄芩素和黄芩苷与人血清白蛋白相互作用的光谱研究

采用荧光光谱、紫外-可见光谱和表面增强拉曼光谱研究了黄芩素和黄芩苷与人血清白蛋白的相互作用, 得到了分子间的结合状态和吸附形态方面的信息. 通过比较黄芩素和黄芩苷的普通拉曼和表面增强拉曼光谱, 确立了黄芩素和黄芩苷的正常构象, 同时考察了结合上人血清白蛋白后不同浓度黄芩素和黄芩苷的吸附方式差别.     

傅里哀变换红外发射光谱法研究金属氧化物催化剂 I. 实验建立及氧化钼的还原-氧化研究

本文报导了傅里哀变换红外发射光谱法研究多相氧化物催化剂的实验装置的建立及实验条件的考察。设计加工了一个温度范围宽, 可在各种气氛和真空条件下原位研究氧化物催化剂的红外发射池。以MoO_3为例, 考察了样品厚度, 测试温度对发射光谱的影响。当样品量小于1 mm·cm~(-2)时, 随样品量增加, 谱峰强度线性增加, 但峰形不发生变化。当样品量高于1 mg·cm~(-2)时, 随样品量增加, 谱图严重畸变。随样品温度升高,谱峰强度近似线性增加。并用该方法研究了MoO_3在还原和再氧化过程中表面氧物种的变化。结果表明桥式MO—O—Mo物种比端基Mo=O物种较易还原, 再氧化时, Mo=O物种比Mo—O—Mo物种优先形成。     

Infrared Photodissociation Spectroscopic and Theoretical Study of the HC2nO+ (n=3-6) Cations

The carbon chain cations, HC_2nO⁺ (n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged” [HC_2nO·CO]⁺ cation complexes in 1600-3500 cm^-1 frequency range. The geometric and electronic structures of the [HC_2nO·CO]⁺ complexes and the core HC_2nO⁺ (n=3-6) cations are determined with the aid of density functional theory calculations. These HC_2nO⁺(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.     

3类高关注紫外线吸收剂的前处理与检测技术研究进展

紫外线吸收剂是一种具有强烈吸收紫外线作用的光稳定剂,会对生态环境以及人体健康造成危害,国内外许多国家已制定相关法规限制其使用。该文综述了近几年来国内外关于二苯甲酮类、三嗪类和苯并三唑类3类紫外线吸收剂检测的研究现状,分别对样品前处理与检测技术进行了详细介绍,并对其研究发展趋势进行了展望。     

薄池吸收宽带紫外光度检测器的研制

设计和制作了利用宽带吸收技术进行宽带表观吸光度测定的薄池宽带紫外光度检测器(，large-bandwidth UV absorption detector，简称LBUAD)，并进行了性能表征。该检测器在光学系统上采用氘灯做为紫外光源，通过宽带紫外玻璃得到入射宽带光，并利用中心对称的双透镜聚焦光学系统对宽带光进行聚焦，聚好的光斑通过蓝宝石球进一步会聚后照射吸收池，然后进行检测。毛细管薄池中系列高锰酸钾溶液的表观吸光度测定结果表明：该仪器的动态范围为2-3个数量级，对硝基苯肼的表观吸光度测定结果表明，其检出限达到10^-6AU，基线漂移小于0．001AU／h。与商品DD2000紫外检测器的比较以及在实际电泳分离中的检测进一步表明：该仪器具有很好的检测性能。     

异烟肼与牛血清白蛋白相互作用的光谱和电化学研究

本文用自制L-天冬氨酸修饰电极(PLA/GCE),采用循环伏安法研究了牛血清白蛋白(BSA)与异烟肼(INH)的相互作用,并与荧光光谱法、紫外-可见光谱法进行了比较。使用循环伏安法和荧光光谱法,测得异烟肼与牛血清白蛋白的结合常数K分别为1.544×10~4、1.479×10~4 L/mol,结合位点数均接近1.1。实验测得异烟肼对牛血清白蛋白是静态猝灭。异烟肼的浓度与牛血清白蛋白的荧光强度的降低在2.5×10~(-7)~4.5×10~(-4) mol/L范围内呈线性关系,检出限为1.0×10~(-7) mol/L。BSA的浓度与异烟肼的氧化峰电流的下降在1.0×10~(-9)~5.0×10~(-5) mol/L范围内呈线性关系,检出限为5.0×10~(-10) mol/L。该方法可用于样品中异烟肼和牛血清白蛋白的测定。     

花旗松素与牛血清白蛋白相互作用的光谱和电化学

采用紫外光谱法、荧光光谱法和循环伏安法,研究了牛血清白蛋白(BSA)与花旗松素（taxifolin）的相互作用。 用荧光法和循环伏安法测得花旗松素与BSA的结合常数K分别为1.3×106和1.6×106 L/mol,结合位点数均接近1.3。花旗松素对牛血清白蛋白是静态猝灭。BSA荧光强度的降低与花旗松素浓度在一定范围内呈线性关系,其线性范围为6.00×10-7~2.00×10-5 mol/L,检出限为2.00×10-7 mol/L。花旗松素氧化峰电流的下降与BSA浓度在一定范围内呈线性关系,其线性范围为7.00×10-7~1.00×10-4 mol/L,检出限为3.00×10-7 mol/L。用于合成样品中花旗松素和BSA的测定,结果满意。     

复方丹参提取物高效液相色谱-紫外-蒸发光散射检测指纹图谱的建立

采用紫外/蒸发光散射检测器(UV和ELSD)串联检测技术,建立了复方丹参提取物HPLC/UV/ELSD指纹图谱。运用指纹图谱相似度评价软件,对14批复方丹参提取物HPLC/UV/ELSD指纹图谱进行相似度计算,结果相似度良好。该指纹图谱能同时反映复方丹参提取物中丹参和三七的主要化学组分特征,可有效评价复方丹参提取物的质量稳定性。     

地鳖纤溶活性蛋白(EFP)的分离纯化、红外光谱分析及抑制鸡胚尿囊膜(CAM)血管生成研究

以传统中药材地鳖为原料, 采用匀浆、盐析、硫酸铵分段沉淀、透析和DEAE-52纤维素离子层析等纯化方法, 从其体内分离纯化得到一种纤溶活性蛋白(Fibrinolyric protein of Eupolyphaga sinensis Walker, EFP), 采用SDS-PAGE电泳法对该蛋白进行了分子量和纯度测定, 结果表明, 从地鳖中提取纯化的EFP为相对分子量为41300的单一成分, 具有明显的纤溶活性, 由蛋白质和糖的红外光谱特征吸收峰可推断EFP为一种糖蛋白. EFP对鸡胚尿囊膜新生血管生成有良好的抑制作用, 比阳性对照组(地塞米松组)对鸡胚生长发育影响要小. 地鳖虫纤溶活性蛋白组分具有抑制血管生成的作用, 有可能用于肿瘤治疗.