Modification of atomic collision dynamics by intense ultrashort laser pulses

Abstract

The laser-induced atomic collision process Na(3S)+Ar+ħω→Na(3${\mathrm{P}}_{1/2}$)+ Ar has been studied by use of an intense, off-resonant laser pulse whose duration is shorter than the collision duration. It has been found that at fixed laser intensity the efficiency for exciting the Na(3${\mathrm{P}}_{1/2}$) state is higher for these ultrashort pulses than for pulses with duration longer than the collision duration. This effect is caused by a time-dependent modification of the collision potentials by the intense laser field. A theoretical calculation is in qualitative agreement with the results.