The high resolution rotational spectrum of methyl iodide using a molecular beam spectrometer

Abstract

The hyperfine structure of the J = 5 ← 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.