High resolution photoelectron studies: Electric field gradient splittings of Cd and Sn 4d energy levels in organometallic compounds

High resolution photoelectron spectra of Me₂Cd (Me = CH₃) in the gas phase, and organotin compounds in the solid state show that the 4d⁹ final state produced in the photoelectron experiment splits in the presence of ligand fields. Only the C₂⁰ crystal field term (the term that transforms like the electric field gradient) contributes to the splitting. The 4d_{$\text{3}\text{2}$} splitting in Me₂Cd and trans-Me₂Sn(BzBz)₂ (BzBz = anion of dibenzoylmethane) are 0.21 ± 0.01 eV and 0.35 ± 0.1 eV respectively. The observed 4d_{$\text{5}\text{2}$} linewidth for Ph₄Sn (Ph = C₆H₅) of 0.67 eV indicates that very narrow linewidths can be obtained on molecular nonconducting solids. The constant spin-orbit splitting values, combined with nuclear field gradients from Mössbauer and NQR measurements, strongly indicate that a previously proposed explanation for the increase in apparent spin-orbit coupling in Cd metal is untenable.