Wang Xue-Bin, Woo Hin-Koon, Wang Lai-Sheng, Minofar Babak, Jungwirth Pavel
Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99354, USA.
J Phys Chem A. 2006 Apr 20;110(15):5047-50. doi: 10.1021/jp060138p.
The electronic structure and electron affinity of the acetyloxyl radical (CH3COO) were investigated by low-temperature anion photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of the acetate anion (CH3COO-) were obtained at two photon energies (355 and 266 nm) and under three different temperatures (300, 70, and 20 K) with use of a new low-temperature ion-trap photoelectron spectroscopy apparatus. In contrast to a featureless spectrum at 300 K, a well-resolved vibrational progression corresponding to the OCO bending mode was observed at low temperatures in the 355 nm spectrum, yielding an accurate electron affinity for the acetyloxyl radical as 3.250 +/- 0.010 eV. This experimental result is supported by ab initio calculations, which also indicate three low-lying electronic states observed in the 266 nm spectrum. The calculations suggest a 19 degrees decrease of the OCO angle upon detaching an electron from acetate, consistent with the vibrational progression observed experimentally.
通过低温阴离子光电子能谱和从头算计算研究了乙酰氧基自由基（CH3COO）的电子结构和电子亲和势。利用一种新型低温离子阱光电子能谱仪，在两种光子能量（355和266 nm）以及三种不同温度（300、70和20 K）下获得了乙酸根阴离子（CH3COO-）的光电子能谱。与300 K时无特征的光谱不同，在低温下355 nm光谱中观察到了对应于OCO弯曲模式的分辨良好的振动序列，得出乙酰氧基自由基的准确电子亲和势为3.250±0.010 eV。这一实验结果得到了从头算计算的支持，计算还表明在266 nm光谱中观察到了三个低电子态。计算表明，从乙酸根中脱离一个电子后，OCO角减小了19°，这与实验观察到的振动序列一致。
