PERTURBATION OF ELECTRONIC POTENTIALS BY FEMTOSECOND PULSES - TIME-RESOLVED PHOTOELECTRON SPECTROSCOPIC STUDY OF NO MULTIPHOTON IONIZATION

Femtosecond time-resolved photoelectron spectroscopy (TRPES) is applie d to the study of 2 + 1 multiphoton ionization process in nitric oxide via the gamma, beta and delta-systems. Selective excitation of a give n vibronic state is demonstrated by tuning the intensity of the femtos econd pulse. Rapid modulation in the TRPES spectrum is observed and at tributed to the temporal perturbation of the Rydberg-valence interacti on by the femtosecond pulse. The experiment shows that significant dis tortion to an electronic surface can be introduced by femtosecond lase r pulses commonly available in modem laboratories. Possible applicatio n of the phenomenon to laser controlled chemistry is discussed.