Bulklike Excitations in Nanoconfined Liquid Helium
M. S. Bryan, Timothy R Prisk, T. E. Sherline, S. O. Diallo, P. E. Sokol
Liquid helium confined in porous media provides a model system for studying the effects of confinement, disorder, and reduced dimensionality upon a strongly interacting Bose fluid. The effects of extreme, nanoscale confinement upon its microscopic excitations are not presently understood. Here we show that the lifetime of the roton excitation is unaffected when superfluid helium is confined within cylndrical pores only a few nanometers in diameter. Several previous experiments have suggested that, at sufficiently low temperature, the roton mean free path is set by the restricted geometry. We performed high-resolution, inelastic neutron scattering studies of the roton lifetime in an ordered mesoporous silica. The temperature-dependence of its lifetime are found to be identical to the bulk fluid, implying that the lifetime is not set by the scale of the confinement. Our results demonstrate that the roton excitation undergoes a process analogous to the total internal reflection of light within an optical fiber.
, Prisk, T.
, Sherline, T.
, Diallo, S.
and Sokol, P.
Bulklike Excitations in Nanoconfined Liquid Helium, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922701
(Accessed May 30, 2023)