INFRARED AND MICROWAVE-INFRARED DOUBLE RESONANCE SPECTROSCOPY OF METHANOL EMBEDDED IN SUPERFLUID HELIUM NANODROPLETS

Abstract

Methanol is one of the simplest torsional oscillators, and has been extensively studied in the gas phase by various spectroscopic techniques. At 300 K, a large number of rotational, torsional, and vibrational energy levels are populated, and this makes for a rather complicated infrared spectrum which is still not fully understood. It is expected that in going from 300 K to 0.4 K (the temperature of helium nanodroplets) that the population distribution of methanol will collapse into one of two states; the \textit{J,K} = 0,0 level for the \textit{A} symmetry species, and the \textit{J,K} = 1,-1 level for the \textit{E} symmetry species. This results in a simplified spectrum that consists of narrow \textit{a}-type lines and broader \textit{b}-type lines in the OH stretching region. Microwave-infrared double resonance spectroscopy is used to help assign the \textit{a}-type infrared lines.