Photoionization of the I 4d and valence orbitals of methyl iodide
Photoionization of the I 4d and valence orbitals of methyl iodide
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DOI：
10.1088/1361-6455/ab8c5a
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
R. Forbes;A. De Fanis;D. Rolles;S. Pratt;I. Powis;N. Besley;A. Milosavljević;C. Nicolas;J. Bozek;D. Holland
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文献类型：
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作者：
R. Forbes;A. De Fanis;D. Rolles;S. Pratt;I. Powis;N. Besley;A. Milosavljević;C. Nicolas;J. Bozek;D. Holland
本文从实验和理论两方面研究了碘甲烷中I4d和价轨道的光吸收和光电离动力学。用同步辐射测量了I4d电离阈值附近的总离子产额。在Tamm-Dancoff近似下，用含时密度泛函理论计算的跃迁能和相对强度对观察到的Rydberg态或价态的结构进行了归属。用平面极化辐射在两种极化几何构型下记录的光电子能谱，使得自电离对价电子角分布的影响得以研究。在50.62和52.34 eV的光子能量下，分别与I4d5/2→σ*和4d3/2→σ*跃迁重合，除了价壳层光电子能带外，还揭示了与母体分子的简单光电离无关的特征。由于自旋-轨道耦合和分子场分裂，I-4d主线的高分辨光电子能谱显示出结构。测定了引起(I~4d)−-1电离的五个态的结合能。测量了碘(在CH_3I中)的N45VV俄歇能谱，并用本文得到的核空穴结合能和双电荷态离子的电离能对观察到的结构进行了归属。讨论了实验测定的俄歇电子角分布与表征(I~4d)−_1态分子轴空间排列的理论角分布参数之间的关系。
The photoabsorption and photoionization dynamics of the I 4d and valence orbitals in methyl iodide have been studied both experimentally and theoretically. Synchrotron radiation has been employed to measure the total ion yield in the vicinity of the I 4d ionization thresholds. The observed structure, due to excitations into Rydberg or valence states, has been assigned using transition energies and relative intensities computed with time-dependent density functional theory within the Tamm–Dancoff approximation. Photoelectron spectra, recorded with plane polarized radiation in two polarization geometries, have allowed the effect of autoionization on the valence electron angular distributions to be investigated. The spectra obtained at photon energies of 50.62 and 52.34 eV, coinciding respectively with the I 4d5/2 → σ* and 4d3/2 → σ* transitions, reveal, in addition to valence shell photoelectron bands, features not associated with simple photoionization of the parent molecule. High resolution photoelectron spectra of the I 4d main-lines display structure resulting from spin–orbit coupling and molecular field splitting. The binding energies of the five states contributing to the (I 4d)−1 ionization have been determined. The iodine (in CH3I) N45VV Auger spectrum has been measured and the observed structure has been assigned using the core hole binding energies derived in the present work together with established ionization energies of the doubly charged ion. The experimentally determined Auger electron angular distributions have been discussed in relation to the theoretical angular distribution parameter characterizing the spatial alignment of molecular axes in the (I 4d)−1 state.