Determination of the aluminum content in high-purity germanium by laser multistage photoionization of atoms

A new method is proposed for the determination of the amounts of impurities in high-purity materials. This involves thermal evaporation and atomization of the material in vacuum and selective detection of impurity atoms by laser multistage photoionization via Rydberg states. Aluminum impurities have been recorded in high-purity germanium (aluminum content 2×10^–7%) with a signal-to-noise ratio of around 10².