Development of a program for the calculation of attosecond time-resolved photoelectron spectra and its application to photo-induced electron transfer reactions

时间分辨光电子能谱可用于探测经历化学反应的分子的动力学。为了计算随时间演化的电子态的强场诱导电离或光电子谱的概率作为核间距R的函数，我们结合了束缚电子态动力学的波包传播方法，例如含时（TD）绝热态方法或多组态TD Hartree-Fock方法，与强场多体S矩阵理论。我们的新方法被应用于H^+_2。计算的电离几率作为R的函数与精确网格点法得到的精确电离几率符合得很好。H的电离：在一个临界核间距处大大增强，该距离远大于平衡距离（称为增强电离）。再现了实验观测到的光电子动量角分布。垂直于激光偏振方向的动量分布在零动量附近有一个尖峰。“尖状”分布是由于激发态动力学导致电离。计算了H_2阈上电离的光电子角分布。我们还计算了乙醇和水等多原子分子的电离几率，表明分子内电子动力学是理解增强电离机制的关键。

Time-resolved photoelectron spectroscopy is useful for probing the dynamics of a molecule that undergoes chemical reactions. To calculate the probability of intense-field-induced ionization or photoelectron spectrum of a time-evolving electronic state as a function of internuclear distances R, we combined wave packet propagation methods for bound electronic state dynamics, such as the time-dependent (TD) adiabatic state approach or the multiconfigurational TD Hartree-Fock method, with the intense-field many-body S-matrix theory. Our new approach was applied to H^+_2. The calculated ionization probability as a function of R is in good agreement with the exact one obtained by an accurate grid point method. Ionization of H: is greatly enhanced at a critical internuclear distance which is much longer than the equilibrium one (known as enhanced ionization). The angular distribution of the photoelectron momentum experimentally observed is reproduced as well. The distribution of the momentum perpendicular to the laser polarization direction has a sharp peak near zero momentum. The "cusp-like" distribution is due to excited state dynamics leading to ionization. We then calculated the photoelectron angular distribution of above-threshold ionization of H_2. We have also calculated the ionization probabilities of polyatomic molecules such as ethanol and water molecule to show that intramolecular electron dynamics is the key to understand the mechanism of enhanced ionization.