$\Lambda $ -DOUBLING IN HIGH ANGULAR MOMENTUM STATES: THE PURE ROTATIONAL SPECTRUM OF CoF (X$^{3}\Phi_i$)

Author Institution: Dept. of Chemistry, Dept. of Astronomy, Steward Obsevatory, Univ. of Arizona, Tucson, AZ 85721; Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom; Dept. of Chemistry and Biochemistry, Arizona State Univ., Tempe, AZ 85287The pure rotational spectrum of CoF (X $^{3}\Phi _{i}$) 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 $^{3}\Phi _{i}$), where the effect was not observed