The multichannel recombination in high-order-harmonic generation (HHG) from the asymmetric molecular ion HeH${}^{2+}$ has been investigated by numerically solving the time-dependent Schrödinger equation based on the non-Born-Oppenheimer approximation. In this paper, not only has the physical image in harmonic emission from the asymmetric molecular ion been established, but also the distinguishing of recombination channels has been achieved. Moreover, our quantitative calculations show that the recombination channels from different electronic states make different contributions to HHG. Furthermore, by means of the time-frequency maps, electron-nuclear probability density distributions, and the laser dressed state picture, the physical mechanism of the multichannel recombination has been revealed.

• Received 12 October 2013

DOI:https://doi.org/10.1103/PhysRevA.89.033410