Tunneling Ionization of Atoms

Abstract

As we said in Chap. 1, the condition for tunneling ionization to occur is the inequality γ² ≪ 1, where γ = ω(2E _i )^1/2 / F is the adiabaticity parameter. Recall that ω and F are the radiation frequency and the electric field amplitude for the electromagnetic radiation, and E _i is the binding energy of the initial atomic state. Although the adiabaticity parameter arose in the description of nonlinear ionization from a short-range potential well (Chap. 3), it was shown that it is also applicable to the case of a hydrogen atom. This result is an argument for applying the adiabaticity parameter to complex atoms as well. The rate of tunneling ionization in a monochromatic field (3.1) was discussed for a short-range potential well. The ionization rate for the ground state of hydrogen atom perturbed by a constant electric field is well-known [4.1]: ω = (4/ F) exp (-(-2/3F).