RAMAN-SCATTERING IN DIAMOND AT HIGH-PRESSURE ISOTOPIC EFFECTS

The first-order Raman scattering in natural and C-13-enriched diamonds was measured at high pressures up to 150 kb in a diamond anvil cell. The ratio v(12)/v(13), where v is the frequency of the first-order Ram an line, decreases with pressure. The deviation of the frequency ratio from the limiting classical value of (m(13)/m(12))(0.5) =1.0408, wher e m is the isotopic mass, becomes stronger at high density. This kind of behavior means that the quantum contribution to the physical proper ties of diamond increases with density. This is typical of systems wit h Coulomb interaction, e.g., metals, high-density plasma. (C) 1994 Ame rican Institute of Physics.