Laser spectroscopy of calcium monohydroxide and calcium monodeuteroxide

Abstract

CaOH and CaOD were studied in the gas phase using dye laser spectroscopy. The molecules were produced in a Broida-type oven. Laser excitation spectroscopy was used to study the Ḃ²Σ⁺-X²Σ⁺ transition of CaOD near 5500 Å. The 000-000 band was rotationally analyzed and r₀ structures were established for both states. Like other alkaline earth monohydroxides, CaOD is a linear molecule. For the Ḃ²Σ⁺ state the following bond lengths were found: r(Ca-O) = 1.9697Å and r(O-H) = 0.9179Å, while for the X²Σ⁺ state, r(Ca-O) = 1.9849 and r(O-H) = 0.9207Å. Optical-optical double resonance (OODR) was used to investigate the upper electronic states of CaOH. A ²Π electronic state and three ²Σ vibronic states were observed for the first time in the region 2990 - 3070 Å. For the ²Π state the rotational constant, B°, and the band origin energy, T₀, were calculated: B° = 0.347 cm⁻¹ and T = 32360 cm⁻¹.