15min:

I. PAK, M. WANGLER, D. A. ROTH, M. HEPP, G. WINNEWISSER, I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany; D. SCOUTERIS, B. HOWARD, Physical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.

The absorption spectra of several rare gas--methane (~Rg~=~Ar,~Kr,~Ne) van der Waals complexes associated with the ₄ fundamental vibration of CH₄ were investigated in the 7 µm region. The complexes were produced in a pulsed slit supersonic jet and detected by a tunable diode laser spectrometer. The observed transitions are related to the R(0), P(1), Q(1) and R(1) transitions of the CH₄ molecule in the complex. Analysis of the data is in progress, and the results will be presented at the conference.