ELECTRONIC-STRUCTURE OF LIQUID POLYVALENT METALS STUDIED BY SYNCHROTRON RADIATION PHOTOELECTRON-SPECTROSCOPY

Recent photoemission studies based on a novel sample surface preparation method revealed a breakdown of the weak scattering model for the liquid polyvalent metals such as Sn, Tl, Pb and Bi. However, the observation of the entire valence bands was hindered by UV satellites present when using conventional UV resonance lamps. The elimination of this problem was one motivation to investigate the electronic structure of these liquid metals with synchrotron radiation. It could be confirmed that the valence bands consist of 6s and 6p state dominated sub-bands well separated by true energy gaps for Tl, Pb and Bi. A narrowing of the 6p band takes place in the sequence Bi Pb Tl in accordance with the decrease in the atomic valences from 6p3 to 6p1. At the same time a narrowing of the energy gaps can be observed in this sequence. The similarity of the shape and the change in the widths of the 6p bands reveal a rigid band like behaviour. Almost identical 6s band widths have been found for these metals in contrast to the trends found for the partial 5s and 4s bands of the lighter liquid polyvalent metals. © 1990.