INFRARED DIODE-LASER JET SPECTROSCOPY OF THE VAN-DER-WAALS COMPLEX (N2O)(2)

The rotationally resolved spectrum of the dimer (N2O)(2) has been reco rded in the region of the monomer N2O nu(3) vibrational band using a d iode laser absorption spectrometer which incorporates a multiple-pass cell and a pulsed-jet expansion. A double-modulation technique involvi ng a fast modulation of the laser frequency and a slow modulation of t he gas pulse has been developed in the experiments. The spectrum is co mpletely analysed and the rotational constants and effective structure s are accurately determined for both the ground and the excited vibrat ional states. The centrosymmetric slipped parallel structure of (N2O)( 2) is well explained by an intermolecular potential containing a combi nation of electrostatic interactions between distributed multipoles of different monomers and atom-atom Lennard-Jones potentials to describe the repulsion and dispersion interactions.