MEASUREMENT OF METHYL IODIDE HYPERFINE STRUCTURE WITH A BEAM-ABSORPTION SPECTROMETER

Abstract

The hyperfine structure of the $J = 5 {\leftarrow} 4$ transition of the ground state rotational spectrum of methyl iodide is investigated with a molecular beam-absorption spectrometer. Combining these measurements with the results of conventional spectroscopy allows us to determine with great accuracy the B rotational constant, some of the quartic and sextic centrifugal distortion constants, the two spin-rotation constants of Iodine, and the quadrupole coupling constant. Moreover, it is found necessary to take into account the interaction of centrifugal distortion with quadrupole coupling.