Electron transition dynamics in high-order harmonic generation process from H₂⁺

The high-order harmonic generation from H-2(+) has been theoretically investigated by numerically solving the two-dimensional time-dependent Schrodinger equation. A sharp minimum can be seen in the harmonic spectrum for larger internuclear distance. Moreover, the electron transition process between the ground state and the first excited state competes with the ionization process at larger internuclear distance, which is the main reason of the spectral minimum. By superposing the static electric field and adjusting the orientation angle theta, it is further proved that the electron transition frequency.