HIGH-RESOLUTION INFRARED-SPECTROSCOPY OF SF6 EMBEDDED IN HE CLUSTERS

The infrared absorption spectrum of SF6 embedded in large liquid He-N clusters was studied in the range around 946.3 cm(-1) using a cw diode laser. A sharp peak (fwhm < 300 MHz) accompanied by two weaker satell ite bands of larger halfwidth (approximate to 1 GHz) were recorded for different mean He cluster sizes (<N-0>=1000-5000). The satellite band s are size dependent and can be fit by assuming that the SF6 molecules with several rigidly attached He atoms rotate freely within the He cl uster. Phonon satellites involving several different types of possible vibrations are also considered as a possible explanation.