The method of quantum wave packet dynamics is used to calculate the femtosecond pump-probe photoelectron spectra and study the important roles of the Rydberg state C(2)Pi and the valence state B(2)Pi in the excitation and ionization processes NO molecule. The dynamic information relevant to the C(2)Pi and B(2)Pi states can be obtained from the time- and energy-resolved photoelectron spectra. The transfers of wave packet and population between the C(2)Pi and B(2)Pi states are studied in detail. A part of the Rydberg state wave packet is trapped in the B(2)Pi. (C) 2004 Elsevier B.V. All rights reserved.