Calculating Ionization Transition Rate for Circularly Polarized Fields, Including Non-Zero Initial Momentum

Potassium atoms in circularly polarized laser field whose intensity (I) varies from 2 x 10(12) W/cm(2) to 2.5 x 10(14) W/cm(2) were studied. In the case when there is zero initial momentum, transition rate (that depends only on I) exhibits standard behaviour: as I increases, so thus the rate, until it reaches its maximum value at 1.1 x 10(14) W/cm(2); after that, rate diminishes as I increases. In the case of non-zero initial momentum, transition rate (that now depends on I but additionally on initial momentum, too) exhibits following behaviour: dependence of the rate on I follows standard pattern, it rises with increase of I until it reaches its maximum, and then diminishes. But with increase of momentum, ionization rate gradually diminishes.