The doubly degenerate core-excited Pi state of N2O splits into two due to the static Renner-Teller effect. The lower state, A(1), has a bent stable geometry and the molecule excited to this state starts to deform itself toward this bent geometry. To probe the effect of the potential energy surfaces of the core-excited A(1) states on the nuclear motion, we measure the momenta of the three atomic ions in coincidence by means of the ion momentum imaging technique. We find that the potential energy surface affects the molecular deformation significantly. N2O in the terminal N 1s(-1)3piA(1) excited state is observed to be bent more than that in the central N 1s(-1)3piA(1) excited state. This means that N2O in the terminal N 1s(-1)3piA(1) excited state bends faster than that in the central N 1s(-1)3piA(1) excited state. When the excitation energy is decreased within the 1s(-1)3pi resonances, the nuclear motion in the A(1) states becomes faster. This is interpreted by the notion that the excitation occurs onto the steeper slope part of the potential energy surface of the excited state for the lower excitation energy. The branching ratio of the A(1) excitation increases with the decrease in the excitation energy. (C) 2004 American Institute of Physics.