五氟乙烷的真空紫外光电离光解离

利用同步辐射真空紫外光电离结合飞行时间质谱对五氟乙烷(CHF₂CF₃)进行了光电离光解离的研究，测定了CHF₂CF₃的电离势及该分子主要碎片离子的出现势. 结果表明: CHF₂CF₃的绝热电离势为(12.25±0.10) eV, 主要碎片离子有CF₂CF_{3⁺、CHFCF3⁺、CF2CF2⁺、CF3⁺、CHF2⁺、CHF⁺和CF⁺，其出现势分别为 (13.93±0.10) eV, (15.25±0.10) eV, (15.12±0.10) eV, (13.30±0.05) eV, (13.05±0.08) eV, (19.17±0.10) eV和 (19.56±0.15) eV. 另外，用从头算分子轨道理论计算了解离电离过程中所有碎片的总能量，并给出了电子态及对称性. 根据实验结果和理论计算，分析了可能的解离通道，并得到了分子及母体离子的键解离能等重要的热力学数据.}     

Vacuum Ultraviolet Free-Electron Laser Photoionization Mass Spectrometry of Alpha-pinene Ozonolysis

\begin{document}$\alpha$\end{document}-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds. Molecular identification of key transient compounds during the \begin{document}$\alpha$\end{document}-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved. Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study the \begin{document}$\alpha$\end{document}-pinene ozonolysis. The experiments of \begin{document}$\alpha$\end{document}-pinene ozonolysis are performed in an indoor smog chamber, with reactor having a volume of 2 m\begin{document}$^3$\end{document} which is made of fluorinated ethylene propylene film. Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction of \begin{document}$\alpha$\end{document}-pinene with O\begin{document}$_3$\end{document}. With the aid of quantum chemical calculations, plausible mechanisms for the formation of these new compounds are proposed. These findings provide crucial information on fundamental understanding of the initial steps of \begin{document}$\alpha$\end{document}-pinene oxidation and the subsequent processes of new particle formation.     

氧化偶氮苯的真空紫外光电离与光离解

分子、自由基和离子的电离势及离解能等是重要的物理化学数据 .长期以来 ,这方面实验研究主要使用电子轰击电离法、或光电离方法 ,最近二十年来才逐渐出现了一些使用同步辐射光电离质谱方法进行分子、自由基光电离和光解离研究 [1－ 3].目前使用同步辐射光电离质谱法研究的对象绝大多数为结构较简单的小分子 ,最近我们使用本实验室光电离质谱及符合装置 ,对对硝基苯乙酮 [4]、对硝基苯乙醚、 对羟基偶氮苯等固体有机化合物进行了系统的研究 ,取得了一些进展 .　　偶氮染料呈现多种颜色 ,它是染料中品种最多、应用最广的一类合成染料 .偶氮染…     

二茂铁的同步辐射光电离

The vacuum ultraviolet photoionization of ferrocene has been studied by using synchrotron radiation and a time-of-flight（TOF）mass spectrometer. The photoionization TOF mass spectrum and photoionization efficiency （PIE）curves of some ions were measured. VUV absorption by ferrocene results in Fe（C5H5）2+,FeC5H5+,Fe+,FeC3H3+,FeC3H+,C10H9+,C10H8+ and C5H6+. The ionization potential（IP）of ferrocene is determined to be （6.78±0.05）eV. The appearance potential（AP）of the fragment FeC5H5+ was measured to be（13.40±0.10）eV. In addition,theoretical calculations with the density functional method B3LYP and the basis set 6-31G（d）have been carried out. The calculation result shows that the ionization potential of ferrocene is 6.16 eV,which is smaller than that from the experiment because the ionization potential from calculation is adiabatic value and the experimental result is vertical value. Due to the limited available computational cost,the case of the electron spin S=1/2 for Fe is only considered,which may lead to some low precision in calculation. So the calculation result is just as references. The appearance potential of FeC5H5+ is 12.17 eV,which is also smaller than the experimental value. According to the experimental and calculation results,the bond energies of D0（FeC5H5+-C5H5）,D0（Fe+-C5H5）,D0（C5H5-Fe+-C5H5）have been evaluated and the possible channels of dissociation photoionization have been analyzed. Sequential elimination of C5H5 ligands is a major dissociation channel,but concerted elimination of two C5H5 ligands also takes place.     

3-氯-1，2-环氧丙烷的同步辐射光电离

杂环类化合物在自然界中分布十分广泛,且许多具有生物活性,它们大多数在生物的生长 发育、遗传和衰亡过程中起着关键的作用［１,２］．含氧三元杂环体系是最基本、最简单的杂环化合 物,分子中的含氧三员环,具有很大的张力,且存在很强的极性共价键,使其易于发生定向开环 反应,具有高度反应性．利用光电高质谱法对这类分子进行光电离与光离解研究,可以获得这 类物质一些重要的物理化学数据． 我们已对环氧乙烷和环氧丙烷进行了光电离和光离解研究,并结合量化理论计算分析了 它们的光电离解离通道［３,４］,３－氯－１,２－环氧丙…     

Photoionization and Dissociation Study of 2-Methyl-2-propen-1-ol: Experimental and Theoretical Insights

The photoionization and dissociation of 2-methyl-2-propen-1-ol (MPO) have been investigated by using molecular beam experimental apparatus with tunable vacuum ultravioletsynchrotron radiation in the photon energy region of 8.0-15.5 eV. The photoionization efficiency (PIE) curves for molecule ion and fragment ions: C₄H₈O⁺、C₄H₇O⁺、C₃H₅O⁺、C₄H₇⁺、C₄H₆⁺、C₄H₅⁺、C₂H₄O⁺、C₂H₃O⁺、C₃H₆⁺、C₃H₅⁺、C₃H₃⁺、CH₃O⁺、CHO⁺ have been measured, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions have been obtained. The stable species and the first order saddle points have been calculated on the CCSD(T)/cc-pvTZ//B3LYP/6-31+G(d,p) level. With combination of theoretical and experimental results, the dissociative photoionization pathways of 2-methyl-2-propen-1-ol are proposed. Hydrogen migrations within the molecule are the dominant processes in most of the fragmentation pathways of MPO.     

二乙基锌的同步辐射真空紫外光电离光解离

利用同步辐射光源和反射式飞行时间质谱, 在超声冷却条件下对二乙基锌(ZnC4H10)进行真空紫外(VUV, 能量范围为8-22 eV)光电离光解离研究. 实验获得ZnC4H10的光电离质谱图; 通过测量各碎片离子的光电离效率(PIE)曲线, 获得ZnC4H10的电离势(IP=8.20±0.05 eV)及其碎片离子(ZnC2H5+、ZnH+、Zn+、C2H5+、C2H3+等)的出现势. 根据实验结果, 并结合相关文献所给的热力学数据, 推导出这些主要碎片离子的生成焓, 并分析它们可能的解离通道和主要离子的分支比. 结果表明, 其主要解离通道是母体离子发生Zn—C 键的断裂形成ZnC2H5+和C2H5+离子, ZnC2H5+离子再进一步解离形成Zn+离子, 并且含锌碎片离子的丰度占75%以上.     

van der Waals团簇ArHCl的光电离研究

用同步辐射光源和光电离质谱研究了分子束中ArHClvanderWaals（vdW）团簇的光电离过程．测量结果表明，分子束中的ArHCl的浓匠与气源压力近似满足如下关系式：a（ArHCl）％＝179×10-8.首次给出了ArHCl团簇的光电高效率曲线，并测得ArHCl 的出现势为12.52±0.03eV。根据实验测量的HCl和ArHCl的电高能，计算出Ar－HCl 的解高能为022±0.03eV.用Gaussian－94w量化程序计算出解高能约为0.16eV.实验表明当团簇内的Ar电离时，ArHCl 质谱峰强度明显低于预计的强度，是由于体系电离后发生了电荷转移及解离过程．     

Vacuum ultraviolet photoionization and photoelectron studies in the new millennium: recent developments and applications

Vacuum ultraviolet (VUV) photoionization mass spectrometry and photoelectron spectroscopy have played a central role in providing energetic and spectroscopic information for neutrals and cations. The most important data obtainable in a VUV photoionization and photoelectron experiment are ionization energies and 0 K ion dissociation thresholds or appearance energy (AE), from which 0 K bond dissociation energies for neutrals and cations can be deduced. The recent developments in VUV lasers and third-generation synchrotron sources, together with the introduction of the pulsed-field ionization (PFI), photoelectron (PFI-PE), and PFI-photoion (PFI-PI) methods, have revolutionized the field of photoelectron and ion spectroscopy by significantly improving the energy resolution to the range of 0.025–1.0 meV (full width at half maximum, FWHM). These resolutions, which make possible the measurement of photoelectron spectra for many simple molecules at the rotational-resolved level, are ≈100-fold better than those observed in traditional photoelectron studies, making the PFI-PE technique a true spectroscopic method. The recent introduction of the synchrotron-based PFI-PEPICO scheme has shown that AE values for a range of molecules can be determined with an unprecedented precision limited only by the PFI-PE measurement. The synchrotron-based PFI-PEPICO and PFI-PI schemes show great promises for future studies of state- or energy-selected ion-dissociation dynamics and energy-selected ion-molecule reaction dynamics. Further improvement in energy resolution for PFI-PE and PFI-PI measurements has been demonstrated using the two-color photo-induced Rydberg ionization (PIRI) spectroscopic scheme, which involves the photo-induced ionization of intermediate long-lived high-n ( n≥100) Rydberg states. The incorporation of this method by VUV photoexcitation to prepare intermediate high-n ( n≥100) Rydberg states is also expected to greatly increase the energy range of PFI studies. The availability of this array of laser- and synchrotron-based PFI methods, including PFI-PE, PFI-PEPICO, PFI-PI, PFI-ion-pair, and PIRI schemes, ensures an exciting and bright future for VUV photoionization and photoelectron studies in the new millennium.     

乙苯光电离的实验研究

利用真空紫外同步辐射和反射式飞行时间质谱研究了乙苯分子的光电离, 通过测量母体分子的光电离质谱(PIMS)以及母体离子和主要碎片离子的光电离效率曲线(PIEs), 确定了乙苯分子的电离能IE(C8H+10)=(8.66±0.02) eV, 主要碎片离子C7H+7和C6H+6的出现能分别为(10.81±0.02)和(10.99±0.02) eV; 利用经验公式计算出产生碎片离子C7H+7和C6H+6需要的解离能(Ed)分别为(2.15±0.04)和(2.33±0.04) eV. 结合相关的热化学参数, 推算出C8H+10, C7H+7和C6H+6的标准生成焓分别为865.5, 927.2和1037.9 kJ/mol. 为进一步研究乙苯的大气光氧化反应机理提供了参考.     

利用同步辐射测定NH_3中键的离解能D_0（H_2N—H）及D_0（H_2N~＋－H）

利用同步辐射测定ＮＨ_３中键的离解能Ｄ_０（Ｈ_２Ｎ—Ｈ）及Ｄ_０（Ｈ_２Ｎ~＋－Ｈ）齐飞，盛六四，俞书勤，张允武（中国科学技术大学国家同步辐射实验室，近代化学系，合肥，２３００２６）关键词同步辐射，光电离，氨分子，离解能ＮＨ３分子中Ｎ—Ｈ键离解能的精确测...     

间硝基苯胺的同步辐射光电离研究

利用同步辐射光电质谱法对间硝基苯脘进行了研究，测得了其电离势ＩＰ为９．６６０．０５ｅＶ，以及一些碎片离子出现势ＡＰ，计算出离解能Ｄ０（Ｎ２Ｏ－Ｃ６Ｈ６Ｎ＾＋）和离子生成焓ΔＨｆ（Ｃ６Ｈ６Ｎ＾＋）。给出了间硝基苯胺的同步辐射同离质谱图，并对主要碎片离子的产生过程进行了初步分析。     

对硝基甲苯的同步辐射光电离研究

光电离对硝基甲苯（PNT）可获得其电离势及碎片离子的出现势，并由此推断出离子产生的可能通道．目前尚未见到有关PNT光电离研究的报道，仅George等［‘j使用电子轰击电离质谱测得过它的电离势．我们使用同步辐射光电离质谱测得了PNT的电离势和8种碎片离子的出现势，给出了飞行时间（TOF）质谱图，归属了质谱中的主要离子峰，初步分析了光解离电离通道．1实验部分实验装置由阈值光电子一光离子符合（TPEPICO）装置改造而成［’，’］，光电离室上方的四极质谱计由TOF质谱计代替，下方的四极质谱计由盛固体样品的小炉取代．样品蒸…     

Experimental and Theoretical Study on Dissociative Photoionization of Cyclopentanone

The dissociative photoionization of cyclopentanone was investigated by means of a reflectron time-of-flight mass spectrometer (RTOF-MS) with tunable vacuum ultraviolet synchrotron radiation in the photon energy range of 9.0-15.5 eV. The photoionization efficiency (PIE) curves for molecular ion and fragment ions were measured. The ionization energy of cyclopentanone was determined to be 9.23\begin{document}$\pm$\end{document}0.03 eV. Fragment ions from the dissociative photoionization of cyclopentanone were identified as C\begin{document}$_5$\end{document}H\begin{document}$_7$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_5$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_8^+$\end{document}/C\begin{document}$_3$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_5^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_4^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_5^+$\end{document} and C\begin{document}$_2$\end{document}H\begin{document}$_4^+$\end{document}. With the aid of the ab initio calculations at the \begin{document}$\omega$\end{document}B97X-D/6-31+G(d, p) level of theory, the dissociative mechanisms of C\begin{document}$_5$\end{document}H\begin{document}$_8$\end{document}O\begin{document}$^+$\end{document} are proposed. Ring opening and hydrogen migrations are the predominant processes in most of the fragmentation pathways of cyclopentanone.     

Vacuum Ultraviolet Irradiation of Polymers

The interest in incoherent sources for wavelength-selective photochemistry has increased lately, but little is still known about the behavior of polymers when exposed to far UV and vacuum UV (VUV) radiation. The same dearth of information exists regarding UV (VUV) radiation emitted by low-pressure plasmas during polymer treatment. In order to study VUV-UV effects on several polymers (polyethylene - PE, polystyrene - PS, hexatriacontane - HTC, and poly(methyl methacrylate) - PMMA), we have used the well-characterized emissions from hydrogen (broad-band emission) and hydrogen/argon mixture (near-monochromatic radiation) plasmas as light sources. During irradiation, samples were kept under vacuum or in a flow of pure oxygen at low pressure; in both cases the radiation fluxes at the sample position have been precisely determined by careful spectroscopic calibration experiments. We have employed a quartz crystal microbalance (QCM) to measure in-situ any possible mass change of the various polymers. Following irradiation, samples were analysed by ellipsometry (for thickness and refractive index), X-ray photoelectron spectroscopy (XPS, to evaluate the near-surface composition and content of various functional groups), and atomic force microscopy (AFM, for surface topography and roughness measurements).     

Vacuum Ultraviolet Photoionization and Dissociative Photoionization of Capecitabine, 50-Deoxy-5-'uorocytidine,and 50-Deoxy-5-'uorouridine

Vacuum ultraviolet (VUV) photoionization and dissociative photoionization of capecitabine and its metabolites, 5'-deoxy-5-fluorocytidine (5'-DFCR) and 50-deoxy-5- fluorouridine (5'-DFUR), were investigated with infrared laser desorption/tunable synchrotron VUV pho-toionization mass spectrometry. Molecular ions (M+) with small amounts of fragments can be found for these compounds at relatively low photon energies, while more fragment ions would be produced by increasing the photon energies. (M-H₂O)⁺, (base+H)⁺, (base+2H)⁺,(base+30)⁺, (base+60)⁺, and sugar moiety were proposed for these nucleoside drugs with similar backbones. Decomposition channels for the major fragments were discussed in de-tail. Moreover, ab initio calculations were introduced to study the dehydration pathways of three fluoro-nucleosides. Corresponding appearance energies for the (M-H₂O)⁺ ions were computed.     

1,4-二氧六环的光电离解离

采用同步辐射光源、飞行时间质谱和分子束方法研究了1．4-二氧六环的光电离解离过程．由光电离效率曲线得出离子产物的出现势，计算了产物的生成焓．若重分析了m／e=28,29.41等离子碎片的解离通道以及离子碎片的可能结构，提出1、4-二氧六环在光电离解离过程中发生了重排反应     

二氯甲烷同步辐射光电离的动力学研究

采用VUV同步辐射光源，在超声射流冷却条件下研究了二氯甲烷（CH2Cl2）光电离及其解离电离的动力学过程，测得CH2Cl2的电离能（IP）为11．32士0．01eV．通过对CH2Cl2光解离电离过程产生的碎片离子的出现势（AP）的测定，并结合有关中性分子的热力学数据，估算出该体系中有关离子的标准生成焓、中性分子和离子型分子中的键能及母体离子的解离能（DE）等一系列热力学数据．对CH2Cl2分子VUV光解离电离通道进行了细致的分析．     

Dissociative Photoionization of Heterocyclic Molecule-Morpholine under VUV Synchrotron Radiation

The radiation damage of biomolecules, in particular with aliphatic compound, has been extensively studied. Morpholine is a typical six-membered aliphatic heterocyclic compound. In the present work, photoionization and dissociation of the morpholine monomer and subsequent fragmentations have been investigated by synchrotron vacuum ultraviolet photoionization mass spectrometry and theoretical calculations. The vertical ionization energy of morpholine monomer is 8.37±0.05 eV, which agrees reasonably well with a theoretical value 8.41 eV of morpholine. Experimentally observed fragmentation of morpholine (m/z=87 amu) gives rise to m/z=86 amu, m/z=57 amu, and m/z=29 amu. Based on experimental and theoretical results, it is found that the m/z=86 amu is produced by losingH atom, the m/z=57 amu is formed by the elimination of CH₂O with a ring-opening process, the m/z=29 amu is generated by further dissociation of the fragment m/z=57 amu (C₃H₇N)⁺ by the elimination of C₂H₄. This finding would provide valuable insight into the photo-damage of aliphatic compounds, which may be related to living cells and other biological system.