Internuclear distance dependent on a single-order harmonic enhancement of hydrogen molecular ion

Generally, driven by a specific laser waveform, a single-order harmonic from the atomic harmonic spectrum can be enhanced, caused by the multiple acceleration-recombination processes. However, in this paper, we found that, driven by the same waveform, a single-order harmonic enhancement is dependent on the internuclear distance of the hydrogen molecular ion. Particularly, at the equilibrium position of 2.0 a.u., a single-order harmonic enhancement with the smaller enhanced ratio can be obtained. As the internuclear distance increases from 3.0 a.u. to 7.0 a.u., a single-order harmonic enhancement is disappeared. When the internuclear distance is larger than 8.0 a.u., a single-order harmonic with a higher enhanced ratio appears again. Further theoretical analyses show that, a single-order harmonic is produced not only from the multiple acceleration-recombination processes of the single ionization, but also coming from the interference of the different ionization-acceleration-recombination processes. According to this principle, we explain the internuclear distance dependent on a single-order harmonic enhancement of the hydrogen molecular ion.

Automated summary

The enhancement of a single-order harmonic in hydrogen molecular ion driven by a specific laser waveform is found to be dependent on the internuclear distance, with a smaller enhanced ratio at an equilibrium position of 2.0 a.u., disappearance at 7.0 a.u., and reappearance at distances larger than 8.0 a.u. The theoretical analyses suggest that the single-order harmonic arises not only from multiple acceleration-recombination processes, but also interference of different ionization-acceleration-recombination processes.