One of the most long-lived fission isotopes, 99Tc, with a half-life of 200000 years, was produced by 99Mo to 99Tc disintegration. Geological interest was therefore focussed on the migration study of Mo in hydroxyapatite. The Mo was introduced by ion implantation, 40nm deep, into pellet samples and the latter were then heated in air. Changes in the shape of the Mo profiles after each annealing step were monitored by means of Rutherford back-scattering spectroscopy. This revealed volatilisation of the Mo. Data arising from X-ray photo-electron spectroscopy suggested that the volatile species which was formed was MoO.

Thermal Diffusion of Molybdenum in Apatite. C.Gaillard, N.Chevarier, N.Millard-Pinard, P.Delichere, P.Sainsot: Nuclear Instruments & Methods in Physics Research B, 2000, 161-163, 646-50