a Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 Japan
b NSLS, Brookhaven National Laboratory, Upton, NY 11973, USA
c ESRF, 38043 Grenoble, France
Abstract:
Inelastic X-ray scattering spectra of lithium (Li)–ammonia solutions with concentrations of 9, 13, and 17 mol.% metal have been measured with 0.05- and 0.38-eV resolution for momentum transfer between 0.18 and 0.56 Å−1. The peak growing with Li-concentration was found around 2 eV, and was assigned to the plasmon of delocalized Li-2s electrons. The plasmon shows a positive dispersion, indicating that exchange–correlation effects in actual nearly free electrons are considerably smaller than expected.