Ion core structure in (N2 O)n+ (n=2-8) studied by infrared photodissociation spectroscopy

Abstract

IR photodissociation (IRPD) spectra of (N2 O)2+ Ar and (N2 O)n+ with n=3-8 are measured in the 1000-2300 cm-1 region. The (N2 O) n+ r ion shows an IRPD band at 1154 cm-1, which can be assigned to the out-of-phase combination of the 1 vibrations of the N2 O components in the N4 O2+ ion; the positive charge is delocalized over the two N2 O molecules. The geometry optimization and the vibrational analysis at the B3LYP/6-311+ G level show that the N4 O2+ ion has a C2h structure with the oxygen ends of the N2 O components bonded to each other. The IRPD spectra of the (N2 O) n+ (n=3-8) ions show three prominent bands at ∼1170, ∼1275, and ∼2235 cm-1. The intensity of the ∼1170 cm-1 band relative to that of the other bands decreases with increasing the cluster size. Therefore, the ∼1170 cm-1 band is ascribed to the N4 O2+ dimer ion core and the ∼1275 and ∼2235 cm-1 bands are assigned to the 1 and 3 vibrations of solvent N 2 O molecules, respectively. Since the band of the N4 O2+ ion core is located at almost the same position for all the (N2 O)n+ (n=2-8) clusters, the C 2h structure of the dimer ion core does not change so largely by the solvation of N2 O molecules, which is quite contrastive to the isoelectronic (CO2) n+ case. © 2009 American Institute of Physics.