Measurement and revised analysis of the torsional combination band of the nonpolar N2O dimer at 2249 cm−1

Abstract

The high-resolution infrared spectrum of the weakly-bound dimer (N₂O)₂ is studied using a rapid-scan tunable-diode laser spectrometer to probe a pulsed supersonic jet expansion. An observed band with c-type rotational structure is assigned as a combination of the intramolecular N₂O ν₁ stretching vibration and the intermolecular out-of-plane dimer torsional vibration, with a vibrational origin at 2249.360 cm⁻¹. The resulting torsional frequency for the nonpolar N₂O dimer is about 21.5 cm⁻¹. The present rotational analysis is completely different from that reported previously for the same band [Hecker et al., Phys. Chem. Chem. Phys., 2003, 5, 2333], which gave a band origin some 1.53 cm⁻¹ lower.