Collision-energy-resolved Penning ionization electron spectroscopy of bromomethanes (CH3Br, CH2Br2, and CHBr3) by collision with He*(2(3)S) metastable atoms.
Collision-energy-resolved Penning ionization electron spectroscopy of bromomethanes (CH3Br, CH2Br2, and CHBr3) by collision with He*(2(3)S) metastable atoms.
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通过与 He*(2(3)S) 亚稳态原子碰撞得到的溴甲烷（CH3Br、CH2Br2 和 CHBr3）的碰撞能量分辨潘宁电离电子能谱。
DOI：
10.1063/1.1769367
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
M. Deleuze
中科院分区：
文献类型：
--
作者：
N. Kishimoto;E. Matsumura;K. Ohno;M. Deleuze
通过碰撞能量分辨潘宁电离电子能谱研究了溴甲烷（CH3Br、CH2Br2 和 CHBr3）与亚稳态 He*(2(3)S) 原子碰撞时的电离。 Br4p 特征的孤对 (nBr) 轨道比 sigma(C-Br) 轨道具有更大的电离截面。部分电离截面的碰撞能量依赖性表明，分子与 He*(2(3)S) 原子之间的相互作用势在 CH3Br 或 CH2Br2 周围具有高度各向异性，而对于 CHBr3 则发现各向同性的吸引力相互作用。在 CH2Br2 和 CHBr3 的 He*(2(3)S) 潘宁电离电子谱 (PIES) 中以大约 2 eV 的电子能量观察到的谱带在紫外 (He I) 光电离谱和理论（三阶代数图解构造）单电子和振动电离谱中没有对应的谱带。所涉及过程的能量分析表明，这些带以及与 sigma(C-Br) 或 piCH2 水平重叠的其他带与解离 (He+ - Br-) 对的自电离有关。类似地，CH3Br 的 He*(2(3)S) PIES 光谱中电子能量约为 1 eV 的谱带归因于目标分子（未识别的）激发态解离释放的自电离 Br** 原子。在 CHBr3 的 He*(2(3)S) PIES 光谱中，可以在孤对 nBr 带下方大约 1 eV 处辨别出另一个自电离 (S) 带。该谱带归因于目标分子 (M**) 的自电离里德伯态衰变成分子离子的振动激发态。研究发现，对于这种转变，入口通道中普遍存在的相互作用势仅仅是有吸引力的。
Ionization of bromomethanes (CH3Br, CH2Br2, and CHBr3) upon collision with metastable He*(2(3)S) atoms has been studied by means of collision-energy-resolved Penning ionization electron spectroscopy. Lone-pair (nBr) orbitals of Br4p characters have larger ionization cross sections than sigma(C-Br) orbitals. The collision-energy dependence of the partial ionization cross sections shows that the interaction potential between the molecule and the He*(2(3)S) atom is highly anisotropic around CH3Br or CH2Br2, while isotropic attractive interactions are found for CHBr3. Bands observed at electron energies of approximately 2 eV in the He*(2(3)S) Penning ionization electron spectra (PIES) of CH2Br2 and CHBr3 have no counterpart in ultraviolet (He I) photoionization spectra and theoretical (third-order algebraic diagrammatic construction) one-electron and shake-up ionization spectra. Energy analysis of the processes involved demonstrates that these bands and further bands overlapping with sigma(C-Br) or piCH2 levels are related to autoionization of dissociating (He+ - Br-) pairs. Similarly, a band at an electron energy of approximately 1 eV in the He*(2(3)S) PIES spectra of CH3Br has been ascribed to autoionizing Br** atoms released by dissociation of (unidentified) excited states of the target molecule. A further autoionization (S) band can be discerned at approximately 1 eV below the lone-pair nBr bands in the He*(2(3)S) PIES spectrum of CHBr3. This band has been ascribed to the decay of autoionizing Rydberg states of the target molecule (M**) into vibrationally excited states of the molecular ion. It was found that for this transition, the interaction potential that prevails in the entrance channel is merely attractive.
DOI：
10.1016/0368-2048(82)85046-9
发表时间：
1982
影响因子：
1.9
作者：
M. Robin
通讯作者：
M. Robin