The low-lying electronic states of CoF

Abstract

The emission spectrum of CoF has been investigated in the 820 nm–3.5 μm spectral region using a Fourier transform spectrometer. The bands were excited in a carbon tube furnace by the reaction of cobalt metal vapor and CF4 at a temperature of about 2300 °C. The bands observed in the 3000–9000 cm−1 region have been classified into three new transitions. The bands with 0-0 R-heads at 3458 cm−1, 3759 cm−1, and 4012 cm−1 have been assigned as the 3Δ1–3Φ2, 3Δ2–3Φ3, and 3Δ3–3Φ4 subbands of the C 3Δ–X 3Φi electronic transition. To higher wave numbers, two bands with R-heads at 8396 cm−1 and 8565 cm−1 have been assigned as the 3Δ2–3Φ3 and 3Δ3–3Φ4 subbands of the D 3Δ–X 3Φi transition. In addition, the bands with R-heads at 6339 cm−1 and 6542 cm−1 have been assigned as the 0-0 3Φ4–3Δ3 and 3Φ3–3Δ2 subbands of the G 3Φ–C 3Δ transition. The G 3Φ–X 3Φ transition has been reported previously as the [10.3]3Φ–X 3Φ transition. The rotational analysis of many bands of these transitions has been obtained and the molecular constants for the two new low-lying excited states have been extracted. Six new band involving the high vibrational levels of ground state (up to v=6) have been identified in the 3Φ4–3Φ4 subband of the G 3Φ–X 3Φ transition. The rotational analysis of these bands provides improved constants for the ground state. We have noticed, as have previous workers, the strong correspondence that exists between the states of transition metal monofluorides and monohydrides. In addition, all of the low-lying states of CoF and CoH are related to the low-lying terms of the Co+ atom. We discuss these correlations between the energy levels of CoF, CoH, and Co+.