NEAR INFRARED AND VISIBLE SPECTROSCOPY OF HYDROCARBONS IN CRYOGENIC SOLVENTS: $CH_{4}, C_{2}H_{4}$, AND $C_{2}H_{6}$ IN LIQUID Ar AND $N^{2}$.

Abstract

Spectra of $CH_{4}, C_{2}H_{4}$, and $C_{2}H_{6}$ pure and in $N_{2}$ and Ar solutions were obtained in the near-IR and visible regions. A resonant cw laser technique that consists of an argon ion laser-dye laser combination modulated at 90 kHz, a piezoelectric detector and a low temperature cell were used to detect absorptions in the visible. Absorptions in the near-IR were observed with a FT-NIR spectrophotometer. Experiments were performed at temperatures between 80 and 120 K. Comparison is made with room temperature gas phase absorption bands. The results indicate that absorption bands, which normally present extensive inhomogeneous congestion due to rotational transitions, hot bands, and combination bands, could be simplified by studying the absorptions in diluted solutions at low temperatures with inert liquefied gases as solvents.