A variable energy photoelectron study of the valence and Hg 5d levels of Hg(CH3)2

Abstract

Using monochromatized synchrotron radiation, the gas phase photoelectron spectra of the Hg 5d and valence levels of Hg(CH3)2 have been obtained between 21 and 100 eV photon energies. Experimental valence band branching ratios have been compared with theoretical branching ratios from MS-Xα calculations. Our results strongly suggest that the ordering of valence levels is 2a″2<3a1<2e′<2e″, rather than 2a″2<3a1<2e″<2e′ from previous theoretical calculations. For the 3a′1 orbital, two shape resonances are predicted at 30 and 50 eV kinetic energy. Only the one at 30 eV is observed. Interchannel coupling with Hg 5d photoemission is important for the outermost 2a″2 and 3a′1 orbitals. Shape resonances and interchannel coupling strongly suggest that He ii:He i cross section ratios cannot generally be used to infer orbital character. The Hg 5d intensity ratio in Hg(CH3)2 differs from that of atomic Hg in the low photon energy region. This effect is probably due to the differences in the outgoing f wave potential between Hg and Hg(CH3)2.