We theoretically study the high-order harmonic generation (HHG) of para-helium and ortho-helium with different symmetric spatial configurations. Our time-dependent Schrdinger equation simulations clearly show that the HHG spectra of para-helium and ortho-helium have a distinct difference in the harmonic amplitude. By performing a detailed time-frequency wavelet analysis of the HHG spectra, the distinction between the HHG spectra of para-helium and ortho-helium is ascribed to the different excitation cross-section of the cation of helium. Furthermore, in terms of a simple recollision model, this dependence of the excitation cross-section of the cation on the symmetry of the two-electron wavefunction of helium is revealed.

我们从理论上研究了具有不同对称空间配置的对氦和邻氦的高次谐波产生（HHG）。我们的瞬态薛定谔方程模拟清楚地表明，对氦和邻氦的 HHG 光谱在谐波幅度上存在明显差异。通过对 HHG 光谱进行详细的时频小波分析，可以区分对氦和邻位HHG 光谱的区别。-氦归因于氦阳离子的不同激发截面。此外，就简单的重碰撞模型而言，揭示了阳离子激发截面对氦的双电子波函数对称性的这种依赖性。