Evidence for an instability near twice the Fermi wave vector in the low electronic density liquid metal Li(NH3)(4)
12 March 2001
We report high-resolution inelastic x-ray scattering measurements in the metallic liquid Li(NH3)(4), which to a good approximation can be treated as a dilute alkali metal. We see a well-defined excitation out to large momentum transfers. This excitation shows a strong softening at wave vectors near the first peak in the structure factor, which occurs near twice the Fermi momentum.