Femtosecond time-resolved photoelectron angular distributions probed during photodissociation of NO2

Femtosecond time-resolved photoelectron angular distributions (PADs) are me asured for the first time in the molecular frame of a dissociating molecule . Various stages of the dissociation process, NO2 --> NO((CII)-I-2) + O(P-3 ), are probed using ionization of the NO((CII)-I-2) fragment to NO+(X(1)Sig ma(+)). The PADs evolve from forward-backward asymmetric with respect to th e dissociation axis at short time delays (less than or equal to 500 fs) to symmetric at long time delays (greater than or equal to 1 ps). Changes in t he PADs directly reflect the time dependent separation and reorientation of the dissociating photofragments.