Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Phys Chem A. 2010 Oct 28;114(42):11091-9. doi: 10.1021/jp101930b.
High-resolution photoelectron spectra of the i-methylvinoxide anion are obtained by slow electron velocity-map imaging. The transitions between the anion ground electronic state, X̃ (1)A', and the radical X̃ (2)A'', and à (2)A' states are measured. Franck-Condon simulations of the X̃ (2)A'' ← X̃ (1)A' transition are performed to aid in assigning peaks, yielding several vibrational frequencies for the first time. Additional structure in the spectrum of the X̃ (2)A'' ← X̃ (1)A' transition is attributed to hindered rotor motion of the methyl group. Simulation of methyl torsional states allows identification of the true origin peak, yielding the experimental adiabatic electron affinity, EA = 1.747 ± 0.002 eV, and the à state term energy, T(0) = 1.037 ± 0.002 eV. Comparison with the fully deuterated isotopologue further supports the assignment of hindered rotor progressions. The favored methyl rotor position is eclipsed in the radical X̃ state and staggered in the anion X̃ and radical à states.
通过慢电子速度映射成像获得了异甲基氧化乙烯阴离子的高分辨率光电子能谱。测量了阴离子基态 X̃（1）A'与自由基 X̃（2）A''和Ã（2）A'态之间的跃迁。对 X̃（2）A''→X̃（1）A'跃迁的 Franck-Condon 模拟有助于峰的分配，首次获得了几个振动频率。X̃（2）A''→X̃（1）A'跃迁光谱中的附加结构归因于甲基的受阻转子运动。对甲基扭转态的模拟允许识别真实的起始峰，从而得出实验的绝热电子亲和力 EA=1.747±0.002eV 和Ã态项能量 T(0)=1.037±0.002eV。与完全氘代同位素物的比较进一步支持受阻转子进展的分配。在自由基 X̃态中，甲基转子处于重叠位置，在阴离子 X̃和自由基 Ã态中处于交错位置。
