Knowledge Bank

We have recently measured the rotational spectrum of $X2\Pi HF+$ by laser magnetic resonance; this measurement continues our study of the hydrogen halide ion series $(HCl+,HBr+\dots )$. $\Lambda$-doubling and hyperfine structure from the halide nucleus was resolved in each case; for $HF+$, hydrogen hyperfine structure was observed as well. The magnetic resonance rotational transitions, augmented by combination differences from optical data, were analyzed using a Zeeman Hamiltonian in a single, weighted least squares fit. Eight molecular constants were determined. Current work is directed towards measuring the rotational spectrum of $DF+$.