The electronic structure of liquid heavy alkali metals from electron spectroscopy

The first investigation of the liquid alkali metals K, Rb and Cs by photoelectron spectroscopy has been performed, complementing previous studies of liquid Li and Na. The shallow bands of these metals enable in some cases their entire investigation by rather unconventional satellite lines of a noble gas discharge lamp. The trend found for the light alkali metals is continued, i.e., a systematic narrowing of the valence bandwidth with increasing atomic mass. The photoemission bandwidths appear to be significantly reduced compared with both the free electron model (FEM) and calculated photoelectron spectra based on ab initio calculations of the electronic structure. The triangular shape of the valence band spectra is reasonably reproduced by the calculated spectra indicating a distinct binding energy dependence of the partial photoelectric yields.