A system for single-crystal elastic and inelastic x-ray scattering studies of condensed gases at pressures to 300 MPa and temperatures to 4 K

A versatile system, operating at pressures to 300 MPa and temperatures to 4 K, has been designed and used for a variety of elastic and inelastic x-ray scattering studies of single crystals of condensed gases. Sintered Be sample cells of volumes 15 endash 30 mm3 are used. Pressure generation is clean and well controlled. Excellent temperature control allows monitoring of phase transitions associated with solidification and melting. The system has very low background and, combined with the high-intensity of synchrotron radiation, is well suited to studies of low-intensity signals. It has been used for 4He in q-dependent studies of fcc lattice dynamics and diffuse scattering and to study thermal defect properties through lattice parameter measurements. In addition, its application to inelastic scattering studies of hcp 4He at 1.5 eV and 10 meV resolution have yielded results about electronic and phonon excitations, respectively. The system can also be used to study other crystalline compounds; in particular, an application has been made to lattice parameter measurements on C2F6. copyright 1996 American Institute of Physics