Hyperfine structure in the electronic spectra of the CdH and CdCH3 radicals

Abstract

Magnetic hyperfine interactions in the ground and first excited states of CdH and CdCH₃ were studied using high resolution electronic spectroscopy. Hyperfine splittings associated with the H nucleus were observed in the X state of CdH; hyperfine splittings associated with ¹¹¹Cd and ¹¹³Cd were observed in both the ground and first excited states of CdH and CdCH₃. The hyperfine parameters of CdH were found to be similar to the corresponding parameters of CdCH₃. Comparison of the ground state molecular hyperfine constants with values determined in an Ar matrix electron paramagnetic resonance (EPR) study [L. B. Knight, Jr. and W. Weltner, Jr., J. Chem. Phys. 55, 2061 (1971)] indicates clearly a shift of unpaired electron spin density towards Cd, in the matrix. The excited state molecular hyperfine constants indicate that the unpaired electron essentially resides in a Cd 5p_π orbital.