DETECTION OF AR-CH4 COMPLEXES IN THE 7 MU-M REGION BY DIODE-LASER SPECTROSCOPY

The absorption spectrum of the Ar-CH4 van der Waals complex was measur ed for the first time in the 7 mu m region. The complexes were produce d in a pulsed slit supersonic jet and detected by a tunable diode lase r spectrometer with 40 MHz spectral resolution. The strongest absorpti on features of the Ar-CH4 complex were observed in the spectral region 1310.57-1311.05 cm(-1), located between the Q(1) and the R(0) lines o f the v(4) fundamental band of the methane monomer. It was found that the newly detected absorption lines belong to three Q-branches of the Ar-CH4 complex. The transitions of these Q-branches are related to the Q(1) transition in the v(4) fundamental band of the methane molecule, which can rotate almost freely inside the complex. The three Q-branch es have been assigned.