Two approaches with X-ray excitation sources directly inside a sample have been examined: mixing a sample in solution with a radioisotope or bombardment of a solid specimen with a radioactive ion beam. The radioisotopes used weere 3H, 35S, 125I, with detection limits of, for example, 20 g/g for Ag excited by a 125I implant of 75 kBq; 100 g/g for Ti excited by a 3H implant of 7 MBq. For comparable detection limits, the source strengths required are 103 less than that needed with external sources. The elemental coverage and the capabilities for simultaneous multielement detection are similar to "conventional" XES. In the beam implant mode, the spot size and energy of the beam provide for spatially resolved in situ X-ray excitation at a desired location inside a solid. 1982.
