In the present work undoped natural (100)-, (111)- and (110)-oriented diamonds were exposed to microwave deuterium plasma. Secondary ion mass spectroscopy in static mode showed that surface deuterium concentration was the highest for (110) surface and the lowest one for (100)-oriented diamond. Secondary ion mass spectroscopy depth profile measurements unambiguously revealed the bulk diffusion of deuterium in the concentration of 1020 to 1021 atoms/cm3. Relative bulk concentrations of deuterium in the three differently oriented diamonds retained those on the surface. The measured diffusion length of deuterium was ~0.6μm. These results support previously performed theoretical calculations and clarified the data previously obtained from absolute quantum photo-yield measurements of hydrogenated natural diamond.Bulk Diffusion of Microwave Plasma Activated Deuterium into Undoped Natural Diamond. Laikhtman, A., Hoffman, A., Cytermann, C.: Applied Physics Letters, 2001, 79[8], 1115-7