Impulsive stimulated scattering of molecular solids and metal surfaces under extreme conditions in a diamond anvil cell

Abstract

Impulsive stimulated scattering is utilized to study the acoustic and mechanical properties of both transparent molecular solids and opaque crystalline metal surfaces. Scattering measurements have been performed on oriented molecular crystals under high pressure conditions in a diamond anvil cells. The ISS technique offers an accurate and robust method of obtaining bulk and surface acoustic velocities of molecular and metallic crystals under extreme conditions without the need for physical contact with the sample. Specifically, directionally resolved impulsive thermal Brillouin scattering has been used to obtain acoustic velocities for oriented crystals of ice VI and ice VII in a high pressure diamond anvil cell. The elastic constants determined from these measurements compared favorably with classical Brillouin scattering results. Impulsive stimulated scattering (ISS) has also been used to obtain the directional dependence of the surface acoustic wave (SAW) velocity on oriented crystal surfaces of metals such as aluminum (111) and nickel (100). The orientationally dependent ISS results for Ni (100) are compared with classical Brillouin scattering measurements, as well as surface acoustic wave calculations utilizing bulk elastic constants.