Microwave spectroscopy of chlorine dioxide: Centrifugal distortion,spin-rotation interaction,and hyperfine interaction constants of 35ClO2 and 37ClO2

Forty-six and fifty-five ground-state rotational transitions of ³⁵ClO₂ and ³⁷ClO₂, respectively, were newly identified in the frequency region of 8–75 GHz. Most of the absorption lines previously reported were remeasured. Centrifugal distortion constants up to sextic ones were derived for both isotopic species. In order to reproduce the observed fine structures satisfactorily, an analysis with the spin-rotation interaction Hamiltonian which included quartic as well as quadratic terms in (electronic spin or rotational) angular momenta was necessary. More precise hyperfine constants were also determined.