IR photodissociation (IRPD) spectra of (N2O)(2)(+)center dot Ar and (N2O)(n)(+) with n = 3-8 are measured in the 1000-2300 cm(-1) region. The (N2O)(2)(+)center dot Ar ion shows an IRPD band at 1154 cm(-1), which can be assigned to the out-of-phase combination of the v(1) vibrations of the N2O components in the N4O2+ ion; the positive charge is delocalized over the two N2O molecules. The geometry optimization and the vibrational analysis at the B3LYP/6-311+G* level show that the N4O2+ ion has a C-2h structure with the oxygen ends of the N2O components bonded to each other. The IRPD spectra of the (N2O)(n)(+)(n = 3-8) ions show three prominent bands at similar to 1170, similar to 1275, and similar to 2235 cm(-1). The intensity of the similar to 1170 cm(-1) band relative to that of the other bands decreases with increasing the cluster size. Therefore, the similar to 1170 cm(-1) band is ascribed to the N4O2+ dimer ion core and the similar to 1275 and similar to 2235 cm(-1) bands are assigned to the v(1) and v(3) vibrations of solvent N2O molecules, respectively. Since the band of the N4O2+ ion core is located at almost the same position for all the (N2O)(n)(+)(n = 2-8) clusters, the C-2h structure of the dimer ion core does not change so largely by the solvation of N2O molecules, which is quite contrastive to the isoelectronic (CO2)(n)(+) case.