空间波函数的对称性对氦原子双光子双电离过程中电子关联的影响

通过数值求解含时薛定谔方程，研究了氦原子具有对称空间波函数的1s2s 1S态和具有反对称空间波函数的1s2s 3S态分别作为初态的双光子双电离过程. 结果表明，对于初态为单重态1s2s 1S的双光子双电离过程，两个电离电子的能量分布随激光脉冲持续时间的增加呈现由单峰到双峰的变化，这里的单峰和双峰分别意味着两个电离电子主要携带相等和不等的能量；然而对于初态为三重态1s2s 3S的双光子双电离过程，两个电离电子的能量分布随激光脉冲持续时间的增加总是保持双峰结构. 这些结果表明当原子的初态处于反对称空间波函数时，两电子的空间密度分布具有较少的重叠，从而导致电子在超短激光脉冲中电离时电子关联能无法平均分配.

Effect of the symmetry of spatial wave function on the electron correlation in the two-photon double ionization process of helium

Two-photon double ionization (TPDI) process of helium is investigated by solving the time-dependent Schr?dinger equation, which the initial state is chosen as the singlet state 1s2s 1S that is symmetric space wave function and as the triplet state 1s2s 3S that is asymmetric space wave function separately. The results show that the energy distribution of two ionized electrons change from one single hump into double humps as the laser pulse duration increases for the TPDI process with the initial state being the singlet state 1s2s 1S, where the single hump (double humps) means that two ionized electrons mainly carry equal energy (unequal energy). However, the energy distribution of two ionized electrons keeps the double humps as the laser pulse duration increases for the TPDI with initial state being the triplet sate 1s2s 3S. These results indicate that the electronic correlation energy cannot be shared equally as the initial state of the atom is the triplet state in the DPDI process, where the overlap between the density distributions of the two electrons is small for the triplet state.