Rotational analysis of the [15.1] A″–[formula omitted]1A′ transition of CuOH and CuOD observed at high resolution with Intracavity laser spectroscopy

Abstract

While mentioned briefly in the analysis of the A∼1A′–X∼1A′ transition of CuOH by Jarman et al. (1991), the 6640 Å band system of CuOH has never been rotationally analyzed. In this work, that band system has been observed and recorded in absorption at high resolution using Intracavity Laser Spectroscopy (ILS), and has been assigned as the v″ = v′ = 0 vibrational band of the [15.1] A″–X∼1A′ transition of CuOH. The CuOH molecules were produced in current-regulated RF discharges formed when 0.40 A was applied to a Cu hollow cathode in ∼500 mTorr of O2 with a trace amount of H2. CuOD molecules were produced in a similar fashion with a discharge current of 0.45 A, and a gas mixture that was ∼80:20% O2:D2. The hollow cathode was located within the resonator cavity of a DCM dye laser that was tuned over the 14,500–16,500 cm−1 range with an optically transparent wedge. Pathlengths of ∼10 km were utilized with the ILS method. The (1,0), (0,1), and (1,2) Ka sub-bands with (Ka′,Ka″) of 63CuOH; the (1,0) and (0,1) Ka sub-bands of 65CuOH; and the (2,1), (1,0), (0,1), (1,2) and (2,3) Ka sub-bands of 63CuOD were included in the rotational analysis. The transitions were fit to a Watson S-reduced Hamiltonian using PGOPHER, and the pure rotational transitions for 63CuOH, 65CuOH, and 63CuOD [J. Chem. Phys., 112, 641 (2000)] were included in the fit. The molecular constants determined by the fit were used to calculate an r0 structure for the [15.1] A″ state. A global perturbation was observed for J′ > 20 in Ka = 1 of the [15.1] A″ state of CuOH, but no perturbations were observed for CuOD. Finally, a correlation diagram has been constructed, comparing the observed and calculated electronic states of the isoelectronic species CuF and CuOH.