ROTATIONAL TEMPERATURE OF METHANE IN SUPERSONIC MOLECULAR BEAM
MetadataShow full item record
Publisher:Ohio State University
Rotational temperature of methane in supersonic molecular beam was claimed to be about 10 $\sim$ 40 K in various conditions. It was found that distribution of the three nuclear spin modifications do not change during the supersonic cooling. A strong deviation from thermal equillibrium was also observed. We re-investigated the rotational temperature of methane by the rovibrational transitions of the \nu$_3$ vibrational band. An infrared spectrometer with cw-OPO laser was used for the observation. The rotational temperature of CH$_4$ derived from transitions up to $J=2$ was 10 K, consistent with the rotational temperature derived for the OCS molecule. Much higher rotational temperature ($\sim$ 70 K) with large diversity was obtained for higher $J$ transitions of CH$_4$, which could be attributed to the incomplete relaxation of rotational-level distribution of light molecule as CH$_4$, a similar situation as the vibrational-level distribution in supersonic molecular beam.
Author Institution: Department of Chemistry, Faculty of Science, Okayama University, Tsushima-Naka 3-1-1, Okayama, Japan
Items in Knowledge Bank are protected by copyright, with all rights reserved, unless otherwise indicated.