Knowledge Bank

The pure rotational spectrum of CoF (X $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Phi i$) has been recorded in the frequency range 270-650 GHz - the first high-resolution study to include all three spin components ($\Omega $ = 4, 3, and 2). CoF was created by reacting cobalt vapor with a mixture of 10% F$2$ in He. Fourteen rotational transitions were recorded. $\Lambda $-doubling was observed in both the $\Omega $ = 3 (5 MHz separation) and $\Omega $ = 2 (100 MHz) spin components, an unexpected result for a $\Phi $ state. In addition, the spectrum is further complicated by the presence of hyperfine interactions arising from both Co (I = 7/2) and F (I = 1/2) nuclei. The complete data set has been fit with a Hund case (a) Hamiltonian, and rotational, fine structure, $\Lambda $-doubling, and hyperfine parameters have been determined. The observation of $\Lambda $-doubling is in contrast to CoCl (X $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Phi i$), where the effect was not observed.