Laser Effects in Photoionization

The spectrum of scattered radiation was computed for an electron, bound initially in the ground state of an isolated hydrogen atom and driven resonantly by the field of a moderately intense (∼1013 W(cm)m2), linearly polarized laser. A numerical solution of the time-dependent Schrödinger equation was performed for the duration of a short (∼30 femtosecond) laser pulse. The spectrum of radiation scattered by this transient state was determined from the autocorrelation function of the electronic acceleration defined as: C a(t) = X m X dt′ d 1s Sa(t′)·a(t′mt) S 1s ¢. The spectral density of emitted radiation was then S(z) = (f 3 /3 ~) X m X dt exp (i z t) C a (t). Numerical results are presented and comparison is made with an earlier less precise formulation.