Abstract
We measured noble gases in artificially shock-produced diamonds in order to examine the size effect of diamond grains on noble gas concentrations and to get the diffusion coefficients of noble gases in diamonds. Noble gases in diamonds were degassed by diffusion process at low temperature below 1700°C, while major degassing occurred at 1700-1900°C by the graphitization of diamonds. As the shock-produced diamonds contain large amounts of noble gases, the diffusion coefficients can be determined at low temperatures even for heavy noble gases. The diffusion coefficients of Ne, Ar and Kr have been estimated to be lower than 10-21 to 10-18 (cm2/sec) at 1000-1400°C.
