Electron Binding in Metals: Grey and White Tin

This is the authors' abstract. We don't add key points for this paper.

Core-electron binding-energy-shift data, obtained from photoelectron spectroscopy, are presented for β-Sn and α-Sn. These data and published results for the M\"ossbauer isomer shift and for internal conversion of ¹¹⁹Sn in the β form have been analyzed in terms of free-atom valence-electron wave functions renormalized to the Wigner-Seitz radii characteristic of the two solids. The three sets of experimental data are readily accounted for in this analysis: β-Sn turns out to have 1.6 ±{} 0.3 $5s$ electrons; and the transition β-Sn→α-Sn is associated with a surprisingly small change, 0.1e to 0.2e, of valence-s to valence-p character. The concepts embodied in this analysis must be applied to the analysis of electron-binding-energy shifts observed in alloys and compounds, both insulating and metallic.