Infrared spectra of N2O-hydrogen complexes

摘要

The infrared spectra of five distinct species of N2O-hydrogen van der Waals complexes (N2O-paraH(2), -orthoH(2), -orthoD(2), - paraD(2), and -HD) were studied in the region of the nu(1) fundamental band of N2O (approximate to2224 cm(-1)) by tunable diode laser spectroscopy in a pulsed supersonic jet expansion. The spectra corresponded to those of T-shaped asymmetric rotors with mainly a-type transitions (DeltaK(a) = 0), plus weaker b-type transitions (DeltaK(a) = +/-1) in the case of N2O-D-2. They were analyzed using a conventional Hamiltonian with quadratic centrifugal distortion parameters. The fitted rotational parameters were consistent with structures having intermolecular separations between 3.25-3.4 Angstrom and angles of about 80degrees between the N2O axis and the hydrogen center-of-mass. These intermolecular distances are about 0.3 Angstrom shorter than those observed previously for the related system, OCS-hydrogen. The band origins were blueshifted relative to the free N2O molecule by from +0.25 to +0.79 cm(-1). These vibrational shifts showed regularities among the different spin and isotopic forms of hydrogen that were analogous to those in OCS-hydrogen. (C) 2002 American Institute of Physics. [References: 28]