Vibrationally resolved N-c and N-t K-shell photoelectron spectra of the dinitrogen oxide have been studied experimentally and theoretically. Vibrational frequencies for the N-c and N-t ls ionized states obtained from the 2D potential surfaces computed by the CCSD(T) method within the equivalent core approximation reasonably agree with the experimental values. Experimental relative intensities of the vibrational structure are reasonably reproduced by the multi-channel Schwinger configuration interaction method (MCSCI) with the computed 2D potential surfaces. Improved relaxed geometries of these core-hole states are obtained from fitting the experimental spectra using the MCSCI calculations and regarding the bond lengths as fitting parameters. (c) 2007 Elsevier B.V. All rights reserved.