| Rutherford Backscattering Spectrometry (RBS) is a powerful ion beam analysis tool with many applications in material analysis. RBS has limitations in resolution, which can be improved by using a magnetic spectrometer. With better resolution, RBS analysis needs more accurate values of stopping power and straggle. Measurements of stopping power and straggle have been made on aluminum, titanium, cobalt, copper, silver, tantalum, and gold. Results show that SRIM stopping power is correct to a few percent. Straggle is overestimated by Bohr's theory, but Chu's modified theory of Bohr's straggle is ten to twenty-five percent less than the measured straggle. The measured straggle has an energy dependence similar to Chu's theory. The fact that straggle is lower than Bohr means that straggle limits RBS mass and depth resolution less than estimations based on Bohr, but greater than the estimations based on Chu. |
