为了了解H2+分子辐射谐波的空间分布, 采用数值求解非玻恩-奥本海默近似的薛定谔方程, 进行了空间均匀和非均匀激光场下H2+分子谐波辐射的空间分布研究。结果表明, 在空间均匀场下, 正向H核辐射谐波强度高于负向H核;在空间非均匀场下, 由于金属结构表面出现的等离子共振增强现象, 谐波截止能量得到延伸;负向H核辐射谐波强度明显高于正向H核,随后通过电离几率、电子布局、电子波函数以及谐波辐射的时频分析可以给出H2+分子谐波空间分布的合理解释。通过叠加谐波谱上的谐波, 可获得一个脉宽为36as的超短孤立阿秒脉冲。该研究对分子谐波的空间分布及阿秒脉冲的输出是有帮助的。

In order to understand spatial distribution of H2+ molecular harmonics, the spatial distribution of H2+ molecular harmonic spectra in spatial homogeneous and inhomogeneous fields was studied through solving non-Bohn-Oppenheimer time-dependent Schrdinger equation. The results show that in spatial homogeneous field, harmonic intensity from positive-H nucleus is higher than that from negative-H nucleus. In spatial inhomogeneous field, due to plasma resonance on metallic nanostructure surface, harmonic cutoff is extended, and harmonic intensity from negative-H nucleus is higher than that from positive-H nucleus. Furthermore, spatial distribution of the harmonics can be explained by ionization probability, electron localization in two nuclei, time-dependent wave function and time-frequency analyses of harmonic spectra. Finally, by superposing a selected harmonics properly, an isolated ultrashort 36as pulse can be obtained. The investigation is helpful for understanding spatial distribution of molecular harmonics and producing attosecond pulses.