			15min:

INFRARED SPECTRA OF THE NE₂-N₂O, AR₂-N₂O TRIMERS.

M. REZAEI, N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, 2500 University Dr., N.W., Calgary, Alberta T2N 1N4, Canada; K. H. MICHAELIAN, Natural Resources Canada, CanmetENERGY, 1 Oil Patch Drive, Suite A202 Devon, Alberta, T9G 1A8, Canada; A. R. W. MCKELLAR, National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada.

Spectra of the van der Waals trimers Ar₂-N₂O and Ne₂-N₂O are studied in the region of the N₂O ₁ fundamental ( sim 2224~cm^-1) using a tunable quantum cascade laser to probe a pulsed supersonic expansion from a slit jet nozzle. Improved data are also obtained for the dimers Ar-N₂O and Ne-N₂O, with the latter representing a significant improvement on the best previous results. As well, a feature in the spectrum is tentatively assigned as the Q-branch of Ar₃-N₂O. The observed vibrational shifts for Ne_n-N₂O are almost exactly linear for n~=~0-2. However, for Ar_n-N₂O the n~=~2 band origin is slightly blue-shifted compared to the linear prediction, and the n~=~3 origin (if correct) is more significantly blue-shifted (by 0.09~cm^-1).