Tunnel ionization of diatomic atmospheric gases (N2, O2) by laser radiation

Abstract

We present the results of calculation of the rates of tunnel ionization of N2 and O2 molecules from the ground and excited vibrational states by linearly polarized laser radiation. These data are necessary for the theoretical description of filamentation. For N2, we consider ionization from the and shells, which give comparable contributions. For O2, we consider ionization from both the ground and excited electronic terms. We demonstrate that for N2, the ionization rate is maximum when the electric field vector of laser radiation is directed along the molecular axis (for shell) or perpendicular to it (for shell), whereas for the O2 molecule, for both electronic states considered, the rates have maxima when the angle between the electric field and molecular axis is equal to 45°.