Valence Photoelectron Spectra of Liquid Methanol and Ethanol Measured Using He II Radiation
Valence Photoelectron Spectra of Liquid Methanol and Ethanol Measured Using He II Radiation
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使用 He II 辐射测量液体甲醇和乙醇的价光电子能谱
DOI：
10.1021/acs.jpca.1c00288
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Suzuki Toshinori
中科院分区：
文献类型：
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作者：
Thuermer Stephan;Shinno Takatoshi;Suzuki Toshinori
使用液体微射流和 He IIα 辐射 (40.813 eV) 测量液体甲醇和乙醇的高分辨率光电子 (PE) 光谱。甲醇的垂直电离能和电离阈值分别确定为 9.70 ± 0.07 和 8.69 ± 0.07 eV，乙醇的垂直电离能和电离阈值分别为 9.52 ± 0.07 和 8.52 ± 0.07 eV。观察到的液体的各个光发射带与本研究中也测量的气体样品的 PE 光谱中的光发射带很好地相关，只是与气体相比，甲醇的液体带位置平均移动了 -1.23 eV，乙醇的液体带位置平均移动了 -1.10 eV。液态甲醇的 5a' 和 7a' 谱带比其他谱带表现出更大的展宽，为此我们尝试用两个分量进行光谱拟合，与液态水的 3a1 谱带的情况类似。液态和气态乙醇的 PE 光谱都比较拥挤，部分原因是反式异构体和高异构体的存在；然而，整体能带位置通常与基于量子化学计算的预测非常一致。测量的 PE 光谱与实验和模拟的 X 射线发射光谱的比较表明，甲醇和乙醇的最低电离带的光谱差异源于 X 射线发射过程中核动力学的参与。
High-resolution photoelectron (PE) spectra of liquid methanol and ethanol were measured using a liquid microjet and He IIα radiation (40.813 eV). The vertical ionization energy and the ionization threshold were determined as 9.70 ± 0.07 and 8.69 ± 0.07 eV for methanol and 9.52 ± 0.07 and 8.52 ± 0.07 eV for ethanol, respectively. Individual photoemission bands observed for the liquids are well correlated with those in PE spectra of the gaseous samples also measured in the present study, except that the liquid band positions were shifted on average by −1.23 eV for methanol and −1.10 eV for ethanol as compared to the gas. The 5a′ and 7a′ bands of liquid methanol exhibit specifically larger broadening than other bands, for which we attempted spectral fitting with two components, similarly with the case of the 3a1band of liquid water. PE spectra of both liquid and gaseous ethanol are congested partly due to the presence of thetransandgaucheisomers; however, the overall band positions are generally in good agreement with predictions based on quantum chemical calculations. Comparison of the measured PE spectra with experimental and simulated X-ray emission spectra indicate that spectral differences in the lowest ionization band of both methanol and ethanol originate from involvement of nuclear dynamics in the X-ray emission process.