Nuclear hyperfine structure in the electronic spectrum of CuCl

Abstract

The (0,0) bands of the D ¹Π-X ¹Σ⁺ and E ¹Σ⁺-X ¹Σ⁺ transitions in CuCl have been recorded by laser excitation spectroscopy. The sample was vaporized in a high temperature nozzle an then cooled by supersonic expansion into a vacuum chamber. The observed rotational temperature was about 15 K. Hyperfine structure for the copper nucleus was easily resolved in the D-X transition. The spectra have been analysed and fitted to appropriate effective hamiltonians. Several molecular parameters have been determined in least-squares fits of the hamiltonian to the data. The implications of these values for the structure of CuCl are discussed. In particular, it is suggested that the D state conforms more closely to a ¹Π state than a ³Δ₁ state, in contradiction to some theoretical calculations.