Knowledge Bank

The $B(1/2)$ and $C(3/2)$ ion-pair excited states of XeF are coupled by the rotational Hamiltonian, producing perturbations in the rotational structure of $B\to X(2\Sigma +)$ transitions involving $v\prime$ levels . A number of $v\prime -v\prime \prime$ bands in the $B\to X$ emission spectrum of the single isotopomer $\mathrm{<mrow\; data-mjx-texclass="ORD">136</mrow>}Xe19$F are analyzed by a deperturbation model to yield improved spectroscopic descriptions of the low-$v$ regions of the B and C states. The C state lies $797cm-1$ below the B state, with $Re=2.473\backslash AA$. The electronic perturbative coupling element for B-C interactions is 6% below the simple Hund's case c-based prediction and just 3% greater than an estimate obtained from a more elaborate case-a approach.