The low-momentum collective ion dynamics of molten potassium has been investigated by means of a high-resolution inelastic neutron-scattering experiment. Collective vibrational modes were found to contribute to the coherent response function over the wave-vector transfer region from 0.2 up to 1 Angstrom(-1). The analysis of the quasielastic features of the dynamic structure factor, due to mainly incoherent scattering, suggests that contributions other than the expected self-diffusion are present. An internally consistent description of the low momentum collective ion dynamics in molten alkali metals was obtained by applying the same data analysis scheme to the present data and those published on Li, Na, Rb, and Cs. The main conclusion is that the Bohm-Staver prescription for the collective-mode velocity does not describe the whole alkali metals series and approaches beyond the random-phase approximation are necessary to treat the electron gas screening of the ion interactions.
Neutron scattering investigation of low-momentum collective ion dynamics in liquid potassium
PETRILLO, Caterina;SACCHETTI, Francesco;
2003
Abstract
The low-momentum collective ion dynamics of molten potassium has been investigated by means of a high-resolution inelastic neutron-scattering experiment. Collective vibrational modes were found to contribute to the coherent response function over the wave-vector transfer region from 0.2 up to 1 Angstrom(-1). The analysis of the quasielastic features of the dynamic structure factor, due to mainly incoherent scattering, suggests that contributions other than the expected self-diffusion are present. An internally consistent description of the low momentum collective ion dynamics in molten alkali metals was obtained by applying the same data analysis scheme to the present data and those published on Li, Na, Rb, and Cs. The main conclusion is that the Bohm-Staver prescription for the collective-mode velocity does not describe the whole alkali metals series and approaches beyond the random-phase approximation are necessary to treat the electron gas screening of the ion interactions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
