A method for the growth and cooling of strain-free single crystals of cryogenic solids

A technique has been developed for growing and cooling single crystals of c ryogenic solids along the solid-vapor saturation line while maintaining a c ondition of negligible mechanical strain. The crystal volumes were similar to 50 mm(3) and optical access was provided for application of Brillouin an d Raman spectroscopies. Single-crystal studies of CH4 and CD4 have been com pleted over the temperature range from the triple point (similar to 90 K) d own to approximately 15 K. In the case of CD4 three distinct solid phases w ere involved. (C) 1999 American Institute of Physics. [S0034-6748(99)01908- 5].