We present the first results using a new technique that combines femtosecon
d pump-probe methods with energy- and angle-resolved photoelectron-photoion
coincidence imaging. The dominant dissociative multiphoton ionization (DMI
) pathway for NO2 at 375.3 nm is identified as three-photon excitation to a
repulsive potential surface correlating to NO(C (2)Pi)+O(P-3) followed by
one-photon ionization to NO+(X (1)Sigma(+)). Dissociation along this surfac
e is followed on a femtosecond timescale. (C) 1999 American Institute of Ph
ysics. [S0021-9606(99)02525-8].