School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China.
Center for Interdisciplinary Studies and Key Laboratory for Magnetism and Magnetic Materials of the MoE, Lanzhou University, Lanzhou 730000, China.
J Chem Phys. 2018 Jun 21;148(23):234304. doi: 10.1063/1.5031210.
We theoretically study the high-order harmonic generation of H and its isotopes beyond the Born-Oppenheimer dynamics. It is surprising that the spectral redshift can still be observed in high harmonic spectra of H driven by a sinusoidal laser pulse in which the trailing (leading) edge of the laser pulse is nonexistent. The results confirm that this spectral redshift originates from the reduction in ionization energy between recombination time and ionization time, which is obviously different from the nonadiabatic spectral redshift induced by the falling edge of the laser pulse. Additionally, the improved instantaneous frequency of harmonics by considering the changeable ionization energy can deeply verify our results. Therefore, this new mechanism must be taken into account when one uses the nonadiabatic spectral redshift to retrieve the nuclear motion.
我们从理论上研究了玻恩-奥本海默动力学之外的 H 及其同位素的高阶谐波产生。令人惊讶的是，在由正弦激光脉冲驱动的 H 的高次谐波光谱中，即使激光脉冲的后沿（前沿）不存在，仍然可以观察到光谱红移。结果证实，这种光谱红移源自于复合时间和电离时间之间的电离能降低，这显然与激光脉冲下降沿引起的非绝热光谱红移不同。此外，通过考虑可变电离能来改进谐波的瞬时频率，可以深入验证我们的结果。因此，在使用非绝热光谱红移来恢复核运动时，必须考虑这种新的机制。
