Abstract

There are many problems of cosmological and geological interest that involve the detection of 1-1000 atoms of a particular isotope in the presence of 10¹⁵−10²⁰ atoms of another isotope of the same element differing by only one or two mass units. These problems include solar neutrino flux, quarks, cosmic rays, geological dating. Interest in the equivalent molecular problem comes In the areas of molecular biology, forensic science, and environmental monitoring. There is no known technique for the solution of most of these problems, although considerable progress toward solutions for specific applications has been made recently. We will describe the difficulties encountered in single-atom (molecule) detection, the directions different groups are taking to circumvent these difficulties, and recent progress toward a solution. Topics discussed will include photoionization, fluorescence, combinations of photoionization and mass spectrometry, nozzle expansions, and solution processing. Special attention will be given to isotope and isobar analysis.

© 1981 Optical Society of America