Infrared diode laser jet spectroscopy of the van der Waals complex (N2O)(2)

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