Reddy V Sivaranjana, Mahapatra S
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
J Chem Phys. 2009 Mar 28;130(12):124303. doi: 10.1063/1.3089870.
Quantum chemistry and dynamics of the ground X (2)B(1) and low-lying excited A (2)A(2), B (2)B(2), and C (2)B(1) electronic states of phenylacetylene radical cation are examined here in striving to understand its photostability, long-lived excited electronic states, and resolved (<10 meV) vibrational energy level spectrum. The electronic potential energy surfaces and their nonadiabatic coupling are computed ab initio. A model Hamiltonian is constructed in a diabatic electronic basis for the nuclear dynamical simulations from first principles. Analysis of electronic structure data reveals the relevance of 24 vibrational degrees of freedom in the quantum dynamics of the X-A-B-C coupled electronic states of the radical cation. The complex vibrational energy level spectrum of this coupled electronic manifold is calculated and assigned. Theoretical results are in excellent accord with the experimental photoelectron spectroscopy data. The agreements and discrepancies of the theoretical results are also recorded and discussed with the mass-analyzed threshold ionization and photoinduced Rydberg ionization and photodissociation spectroscopy results of the X and C electronic states, respectively. The lifetimes of the excited electronic states of phenylacetylene radical cation are estimated from the decay of electronic population and are discussed in relation to the available experimental data.
本文研究了苯乙炔自由基阳离子基态X (2)B(1)以及低激发态A (2)A(2)、B (2)B(2)和C (2)B(1)的量子化学和动力学，旨在理解其光稳定性、长寿命激发电子态以及分辨的（<10 meV）振动能级谱。通过从头计算得到电子势能面及其非绝热耦合。基于第一性原理，在绝热电子基中构建模型哈密顿量用于核动力学模拟。对电子结构数据的分析揭示了24个振动自由度在自由基阳离子X - A - B - C耦合电子态量子动力学中的相关性。计算并归属了该耦合电子体系复杂的振动能级谱。理论结果与实验光电子能谱数据高度吻合。同时，也分别记录并讨论了理论结果与X和C电子态的质量分析阈值电离、光致里德堡电离以及光解离光谱结果之间的异同。根据电子布居的衰减估算了苯乙炔自由基阳离子激发电子态的寿命，并结合现有实验数据进行了讨论。
