Formation of Molecular Superexcited States and Their Dissociation Dynamics

分子超激发态的形成及其解离动力学

• 批准号: 08102005
• 负责人: HATANO Yoshihiko
• 金额: $ 70.4万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Specially Promoted Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08102005/
• 关键词: Superexcited status; Electron energy-loss spectrum; Coincidence; Neutral dissociation; Synchrotron radiation; Fluorescence; Deexcitation; Recombination; 電子エネルギー損失分光法; 窒素分子; 分子超励起状態; 解離; 発光励起スペクトル; 位置敏感型測光システム; 水素分子; 光学的禁制状態; 同位体効果; コインシデン

We have established a new experimental method, i.e. the coincident electron-energy-loss spectroscopy, to investigate dissociation dynamics of molecular superexcited states, especially that of optically-forbidden superexcited states. A vuv photon detector and a coincidence counting system are combined with a specially-designed electron-energy-loss-spectroscopy system for gas phase. An electron energy-loss spectrum of HィイD22ィエD2 in coincidence with H(2p) formation, i.e. a coincident energy-loss spectrum, have then successfully been obtained after careful optimization of experimental conditions and developing a unique normalization procedure for coincidence counting rates. By using this method, we measured an electron energy-loss spectrum of doubly excited states of HィイD22ィエD2 for the first time. It should be emphasized that a large peak due to the forbidden doubly-excited states of HィイD22ィエD2 is observed in the coincident energy-loss spectrum whose position and shape are not explained by … More a conventional theory, which has stimulated some experimental as well as theoretical scientists. Isotope effects in the coincident energy-loss spectra of doubly excited states of HィイD22ィエD2 and DィイD22ィエD2 were also investigated. The coincident energy-loss spectrum of highly excited states of HィイD22ィエD2 near the first ionization potential was measured at the lower incident electron energy, i.e. 30eV. The branching ratio of H(2p) formation is found to be higher for optically forbidden states such as the d, k, n and f states than other allowed states. Since 1999, the measurement for NィイD22ィエD2, as an extension to multi-electron systems, has been started.Various experiments by using synchrotron radiation were done to investigate the dissociation dynamics of optically allowed superexcited states : the precise measurement of photoabsorption, photoionization and neutral dissociation cross sections, that of dispersed vuv-fluorescence excitation spectra (2D FES), and ion-fluorescence coincidence measurement. In addition to them, we have recently succeeded in measuring a dispersed uv/visible-fluorescence excitation spectra by position sensitive detection technique to investigate the dissociation dynamics comprehensively.Collisional deexcitation processes of excited rare gas atoms and electron-ion recombination processes, where the superexcited states play an important role as reaction intermediates have also been investigated by the pulse radiolysis technique. Less

我们建立了一种新的实验方法，即符合电子能量损失谱，用于研究分子超激发态，特别是光禁止超激发态的离解动力学。VUV光子探测器和符合计数系统与专门设计的气相电子能量损失谱系统相结合。经过对实验条件的认真优化和对符合计数率的独特归一化处理，成功地获得了与H(2p)形成相符合的HィイD22ィエD2的电子能量损失谱，即符合能量损失谱。利用这种方法，我们首次测量了H-ィイ-D22-ィエ-D2双激发态的电子能量损失谱。应该强调的是，在重合能量损失谱中观察到了一个由于HィイD22ィエD2的禁忌双激发态而产生的大的峰，其位置和形状没有被…解释更多的是一种传统理论，这激发了一些实验和理论科学家的兴趣。还研究了H-ィイ-D22-ィエ-D2和D-ィイ-D22-ィエ-D2双激发态重合能量损失谱中的同位素效应。在较低的入射电子能量(30 EV)下，测量了H-ィイ-D22-ィエ-D2的高激发态在第一电离势附近的重合能量损失谱。发现d、k、n、f等光学禁止态的H(2p)构型的分支率高于其他允许态。从1999年开始，N-ィイ-D22-ィエ-D2作为多电子体系的延伸，利用同步辐射进行了各种实验，研究了光学允许超激发态的离解动力学：精确测量了光吸收截面、光电离截面和中性离解截面，精确测量了分散真空紫外-荧光激发光谱(2D-FE)截面，并进行了离子-荧光符合测量。此外，我们最近还成功地用位置灵敏探测技术测量了分散的UV/可见光荧光激发光谱，以全面研究离解动力学。我们还用脉冲辐解技术研究了激发稀有气体原子的碰撞去激发过程和电子-离子复合过程，其中超激发态作为反应中间产物起着重要的作用。较少

项目成果

A.Ehresmann et al.: "Dissociative single and double photoionization with excitation between 37 and 69 eV in N_2,"J.Phys.B:At.Mol.Opt.Phys.. 33[3]. 473-490 (2000)

A.Ehresmann 等人：“N_2 中 37 至 69 eV 激发的解离单光电离和双光电离”，J.Phys.B:At.Mol.Opt.Phys.. 33[3]。

K.Onoe et al.: "Selective synthesis of acetylene from methane by microwave plasma reactions,"Fuel. 73. 281-282 (1998)

K.Onoe 等人：“通过微波等离子体反应从甲烷中选择性合成乙炔”，《燃料》。

N. Kouchi: "Coincident electron-energy-loss study of highly excited molecules"Bull. Am. Phys. Soc.. 44. 61 (1999)

N. Kouchi：“高激发分子的同时电子能量损失研究”Bull。

Y. Hatano: ""Physiochemical aspects of atomic and molecular processes in reactive plasmas""Adv. At. Mol. Opt. Phys.. 43. 231-241 (2000)

Y. Hatano：“反应等离子体中原子和分子过程的物理化学方面”

K.Kameta et al: "Photoionization and neutral-dissociation of hydrocarbons in the extreme ultraviolet range" Proc.of International Worksyop on Photoionization. 56 (1997)

K.Kameta 等人：“极紫外范围内碳氢化合物的光电离和中性解离”Proc.of International Worksyop on Photoionization。