Knowledge Bank

Pure rotational transitions within the ground state of deuterium iodide (DI) have been measured over the range $J\prime \prime =2$ to 10 by tunable far-infrared (TuFIR) spectroscopy. The spectra show large electric-quadrupole splittings arising from the $\mathrm{<mrow\; data-mjx-texclass="ORD">127</mrow>}I$ nuclear spin (I = 5/2). A least-squares fit to the measured transitions has resulted in accurate values for the molecular parameters $B,D,eQq,DeQq$ and $Cf$.