The hyperfine structure of the calcium monohalides

Intermodulated fluorescence spectra of the A 2Π–X 2Σ+ and B 2Σ+–X 2Σ+ systems of Ca79Br, Ca81Br, and CaI have been recorded. 79Br, 81Br, and 127I magnetic and electric quadrupole hyperfine structure was observed. The following parameters were determined (in MHz, 1σ uncertainties in parentheses): with eQq set equal to zero in all X 2Σ+ states. The observed hyperfine structure of CaF, CaCl, CaBr, and CaI may be interpreted in terms of halide orbital polarization rather than ionic–covalent mixing of M+X− and MX configurations.