title: Single-crystal Brillouin spectroscopy with CO2 laser heating and variable q.
abstract: We describe a Brillouin spectroscopy system integrated with CO2 laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ∼13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (∼141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm).
authors.affiliation: Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Jin S
authors.initials: JS
authors.lastname: Zhang
authors.affiliation: Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Bass
authors.affiliation: Materials Research Department, Toyota Research Institute of North America, Ann Arbor, Michigan 48105, USA.
authors.forename: Gaohua
authors.initials: G
authors.lastname: Zhu