Infrared spectra of the polar and nonpolar N2O dimers in the 1280 cm−1 region of the ν3 fundamental

The high-resolution infrared spectrum of the polar N2O dimer has been observed in the region of the N2O ν3 fundamental (∼1280 cm−1) using a tunable diode laser to probe a pulsed supersonic slit jet. About 120 rotational transitions were assigned in terms of an a/b hybrid band of a planar asymmetric top molecule with a slipped parallel structure. The vibrational origin was determined to be 1290.21 cm−1, showing a blue shift of 5.31 cm−1 with respect to the monomer band origin. In addition, the spectrum of the nonpolar isomer at 1279.71 cm−1 has been remeasured and analyzed in improved detail. Small but widespread perturbations are noted in this band, which appear somewhat similar to larger effects observed previously in the ν1 + ν3 region for nonpolar (N2O)2.