Orientational ordering in methane condensates in mesoporous SiO2 modifications at low temperatures

The rotational spectra of CH4 at low temperatures have been used to investi gate the disordering influence of a restricted geometry on the orientationa l structure of methane condensates in silicagels and Controlled Pore Glasse s. A cross-over from complete orientational disorder to the partially order ed phase II of pure methane was observed with increasing pore diameter d at d similar to 120 Angstrom.