PHOTOEMISSION FROM LIQUID Li-Pb ALLOYS

Abstract
A photoelectron spectrometer has been developed for the measurement of liquid metals and alloys which are volatile and have melting points up to 1500°C. Low energy (hω = 21.2 eV) photoemission spectra are presented for liquid Li_xPb_1-x alloys for 0 ≤ x ≤ 0.67. For x ≈ 0 they confirm the deviation from the nearly free electron picture characteristic of heavy polyvalent metals (1) showing separated 6s and 6p bands. At higher Li concentrations a broad peak appears at 2.6 eV below the Fermi edge, near the bottom of the Pb 6p band, which is tentatively associated with a bonding state. The Pb 6s band, which lies below -5 eV, is not significantly affected by alloying. The binding energy of the Pb 5d_5/2 level was determined for all compositions. It is suggested that the small shift 0.3 eV towards the Fermi level does not accord with a simple ionic model which involves the complete filling of the Fb 6p shell as the stoichiometric omposition Li₄ Fb is approached.