Lifetime of a hydrogen atom in an intense radiation field

The lifetime of an atom in a high-frequency high-intensity laser field is studied. A coupled-channel formalism is developed, based on a well-known high-frequency theory, that describes the behavior of an atom in a laser field. Numerical results are obtained using a finite-difference approximation in combination with a two-center complex scaling technique. The complex scaling method is also shown to be very well suited for calculations on diatomic molecules. Several numerical results are used to illustrate the qualitative features of the method. We show that our theory is formally (though not in practice) equal to other methods that have been used heretofore. It will be shown that, for high-frequency and high-intensity laser fields, the present method can be used to calculate resonance energies using only a few channels.