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Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method
Published on: February 28, 2014
Phonons, rotons, and layer modes of liquid 4He in aerogel
1Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS/MDN, CEA Grenoble, 38054 Grenoble, France.
Abstract:
We report the first observation of two-dimensional layer modes in both fully filled and partially filled aerogel. Using complementary high-energy resolution and high statistical precision neutron scattering instruments, and two different 87% porous aerogel samples, we show that the three-dimensional (3D) phonon-roton excitation energies and lifetimes of liquid 4He in aerogel are the same as in bulk 4He within current precision. The layer modes are the excitations that distinguish aerogel from the bulk rather than a difference in the 3D roton energy.
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