MOMENTUM-TRANSFER DEPENDENCE OF INELASTIC X-RAY-SCATTERING FROM THE LI-K EDGE

Inelastic x-ray scattering from the K edge of lithium metal at 30 K is measured at momentum transfers q = 8.8 and 97.3 nm(-1) with 80 meV en ergy resolution. The transition from dipolar(1s --> p, q = 8.8 nm(-1)) to monopolar (1s --> s, q = 97.3 nm(-1)) excitations is demonstrated by differences in the spectra reflecting either the p or s partial den sity of slates above the Li Fermi level. The Mahan-Nozieres-De Dominic is theory is utilized to determine both threshold exponents alpha(0) a nd alpha(1) from the present K-edge data.