双色激光场中激光强度和脉宽对线性多原子分子离子电离的影响

 利用强激光场电离和离解分子来研究分子激发态的波包结构是强场物理的重要研究方向。利用短时指数传播子对称分割法和快速傅里叶变换技术，数值求解了一维含时Schr-dinger方程，探讨了双色激光场中激光的基波和谐波强度之间的不同配比以及脉宽对线性多原子分子离子电离的影响。理论计算结果表明：基波和谐波的相对相位为π时，尽管随着激光的基波和谐波强度之间配比的变化，电离几率随原子间距变化的趋势基本保持不变，但在一定的激光基波强度下（1.2×10¹³~1.2×10¹⁵ W/cm²)，激光基波强度的变化可以明显改变电离几率随原子间距变化的趋势。另外，激光脉冲的持续作用可以增强分子的电离，取原子个数为5，基频光波长为800 nm，基波与谐波的强度配比为4，频率配比为2，当其作用时间达到75 fs时，电离基本接近饱和。采用外静电场电离模型能够合理地解释这些现象。

Influence of intensity and pulse width on ionization of linear multi-atom molecular ion in two-color laser fields

The studies of the wavelet structures of the molecular excitations with the high intense laser are very active in the strong laser field physics. The one-dimensional time-dependent Schrdinger equation was numerically solved with the symmetric splitting of the short-time exponential propagator and the fast Fourier transformation, and influence of intensity and pulse with on ionization of linear multi-ation molecular ion in two-color laser fields was researched. The theory results show that the dependence of ionization probability on the atomic distance can be altered obviously with the fundamental wave-field-intensity of 1.2×10~13 ~1.2×10~15 W/cm2, but unchanged with respect to different intensity ratios. In addition, the continuous interaction of laser pulse can enhance molecular ionization, the ionization, however, comes up to saturates when the interaction time reaches 75 fs with given parameters. These results can be explained by the static-electric-field ionization model.