Hyperfine Interaction, Chemical Bonding, and Isotope Effect in ZnH, CdH, and HgH Molecules

ESR spectra of ZnH, CdH, HgH, and HgD molecules in their ground Σ+2 states were measured while trapped in solid argon matrices at 4°K. g tensors and hyperfine structure (hfs) constants for interaction with H, D, 111,113Cd, and 199,201Hg nuclei were observed. Coefficients of approximate LCAO wavefunctions are derived from these magnetic parameters and correlated with chemical bonding trends in the series and with the limiting united-atom model. Replacing H by D in HgH causes an increase of spin density on Hg and a decrease in g∇. This is shown to be largely due to the small decrease in interatomic distance and is discussed relative to other spectroscopic observations.