			10min:

ANTI-HYDROGEN BONDING INTERACTION IN TETRAFLUOROMETHANE-WATER.

A. MARIS, W. CAMINATI, A. DELL'ERBA, P. G. FAVERO, Dipartimento di Chimica "G.Ciamician", Universita' di Bologna, Via Selmi I-40126, Italy.

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The rotational spectrum of the tetrafluoromethane-water (CF₄-W) complex has been assigned in a supersonic expansion through millimeter wave absorption spectroscopy. In order to reach the best experimental conditions mixtures with rather high concentrations of CF₄ (up to 20-30 per cent) in Ar at a pressure of 50 kPa were flown at room temperature and expanded to about 1 Pa through a pulsed nozzle with a 0.35 mm diameter. All measured isotopomers (CF₄---H₂O, CF₄---H₂¹⁸O, CF₄---D₂O, CF₄---DOH) display symmetric top (prolate) spectra, because of the nearly free rotation of the water subunit with respect to CF₄. The first two isotopomers are split into two component lines due to an internal rotation of water along its C₂v axis. The water is linked to CF₄ by a C-F---O, anti hydrogen bond, interaction (see below).