强阿秒XUV激走脉冲下H2^＋分子光电子能谱角分布非对称性

利用2D平面模型，求解了描述定向H2^＋分子和阿秒XUV脉冲相互作用的薛定谔方程，并求得光电子的角度分布．在计算模型中，采用基态1sσg和第一激发态2pσu的等比例混合态作为初始态，而激光脉冲的光子能量大于电离势，强度为10^14 W/cm^2． 计算结果表明，光电子角分布的非对称性和脉冲的宽度密切相关．这种非对称性实际上是由于初始态的基态和激发态的相干振荡而导致的．当使用长脉冲时，这种相干振荡的周期效应就会被平均而消失，从而产生的光电子能谱会呈对称角分布．

Asymmetry of Photoelectron Angular Distributions in Molecules by Intense Attosecond Extreme Ultraviolet Laser Pulses

We present photoelectron angular distribution of the aligned molecular ion H2^＋ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of timedependent Schrodinger equations. Photoionization from a superposition state of the ground 1sσg and the excited 2pσu states with pulses at photon energies above the ionization potential, hω〉Ip, and intensity 10^14 W/cm^2, yields pulse duration dependent asymmetry of photoelectron angular distributions. We attribute the asymmetry to the periodical oscillation of the coherent electron wave packets, resulting from the interference of the two electronic states. For the processes with long pulse durations, such duration dependence is absent and symmetric angular distributions are obtained.