DETERMINATION OF HYDROGEN AND DEUTERIUM IN ZR-2.5NB BY LASER-ABLATION

Laser ablation is investigated as a microsampling technique for determ ining the content and spatial distribution of hydrogen and deuterium i n zirconium alloys. Zr-2.5wt%Nb (Zr-2.5Nb) material is ablated under v acuum with the 1.06 mu m output of a Nd:YAG laser. Elemental H and D i n the ablation plume are detected in a time-of-flight mass spectromete r (TOF-MS) following photo-ionization via the 1s-2s two-photon resonan ce near 243 nm. The laser/surface interaction is shown to be character ized accurately by a simple thermal model and the subsequent ablation is consistent with volume evaporation from the melted alloy. Elemental compositions in the ablation plume are found to represent those in th e alloy. The analytical capabilities of laser ablation sampling are st udied and discussed using various Zr-2.5Nb samples with known deuteriu m concentration gradients and bulk deuterium content. Crown (C) 1998 P ublished by Elsevier Science B.V.