School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, Scotland, United Kingdom.
J Chem Phys. 2013 Jun 7;138(21):214317. doi: 10.1063/1.4807841.
The first vacuum-ultraviolet absorption spectrum of pyridine-N-oxide has been obtained, and has led to the identification of nearly 30 Rydberg states. These states were identified by use of the vibrational envelope ("footprint") of the UV-photoelectron spectrum, and are based on the first to the third ionization energies (IE). The adiabatic IE order, central to the Rydberg state symmetry identification, is confirmed by multi-configuration SCF calculations as: 1(2)B1 < 1(2)B2 < 1(2)A2 < 2(2)B1. Several excited valence state equilibrium structures were determined by multi-configuration SCF and coupled cluster procedures. Multi-reference multi-root CI was used to calculate both Rydberg and valence state vertical excitation energies and oscillator strengths, which were correlated with the experimental measurements.
吡啶-N-氧化物的第一个真空紫外吸收光谱已经获得，并导致了近 30 个里德堡态的识别。这些状态是通过使用紫外光电子能谱的振动包络（“足迹”）来识别的，并且基于第一到第三电离能（IE）。里德堡态对称性识别的核心是绝热 IE 顺序，通过多组态 SCF 计算得到证实：1(2)B1 < 1(2)B2 < 1(2)A2 < 2(2)B1。通过多组态 SCF 和耦合簇程序确定了几个激发价态平衡结构。多参考多根 CI 用于计算里德堡态和价态垂直激发能和振子强度，并与实验测量相关联。
