Determination of few to single atoms by analytical instrumentation and radiochemical processes

Presently, there exist two different methods to reach the boundary of analytical chemistry: the determination of single atoms: 1. Resonanz Ionization Spectrometry (RIS) use the selective multistep excitation and subsequent ionization of gaseous atoms by laser light. By this way, single Cs and Na atoms were detected. - 2. Determination of decay products of a radioactive nuclide allows the identification of a single nuclide of the single α-particle (or spontaneous fission fragment) is unambigously detected. The effectiveness of this procedure was clearly demonstrated by the recent discovery of a single, very short-lived atom of the new element 109 with the Darmstadt Heavy Ion Accelerator, produced by ''cold'' fusion of 209Bi and 54Cr. - Very small amounts of material up to 10-15 g/g (and even lower) uses the ''Accelator-Centered Mass Spectrometry'', by which method negatively charged ions were accelerated in the first step. This method is primarily being used for determination of long-lived, naturally occuring radionuclides like 10Be, 14C, 26Al, 36Cl, and 129I which are formed by cosmic rays interaction, especially for improved and more accurate dating of biological and sedimental materials. It allows higher sensitivity than normal radiometric procedures. The combination of the ACMS-technique with the RIS procedure will allow in future the determination of very small amounts of many elements up to 10-20 g/g. (orig.)