Suppression of ionization of heteronuclear diatomic molecules probed by intense lasers

Abstract

We theoretically investigate the ionization suppression of heteronuclear diatomic molecules and choose NO and NH as examples. These molecules have antibonding molecular orbitals, and hence we expect that the dynamics can be different from those, such as CO, with bonding molecular orbitals we have studied before [Ren and Nakajima, Phys. Rev. A 82, 063410 (2010)]. Calculations are performed within the framework of strong-field approximation. We find that NO generally exhibits a double-core feature at any laser intensity and hence the ionization suppression is significant. However, it is not as significant as that of O${}_{2}$ because the interference between the two electron wave packets arising from the N and O cores upon photoelectron ejection cannot be as strong as that of O${}_{2}$ due to the fact that NO is a heteronuclear diatomic molecule. In contrast, NH exhibits a single-core feature at any laser intensity, since the dominant contribution to ionization comes from the low-energy photoelectron ejections which mainly take place from the neighborhood of the N core. These behaviors of NO (always double-core feature) and NH (always single-core feature) are quite different from that of CO whose ionization behavior gradually changes from the single- to double-core features as the laser intensity increases.