Isotope effects in the infrared spectra of the polar and nonpolar isomers of N2O dimer

The rotationally resolved spectra of 15N15N16O dimer for the polar and nonpolar isomers are studied in the region of the N-N stretching fundamental of the monomer (∼2150 cm−1) using a rapid-scan tunable diode laser spectrometer to probe a pulsed supersonic jet expansion. These spectra are very similar to the corresponding spectra of the normal species, (14N14N16O)2. Structural parameters and vibrational shifts obtained here are compared with those of the normal species and ab initio values. These results confirm that the nonpolar isomer has a centrosymmetric slipped-antiparallel structure while the polar isomer consists of two slipped and (approximately) parallel monomer units.