81Kr detection using resonance ionization spectroscopy

A resonance ionization ion source, in conjunction with a mass spectrometer, was used to count 1000 individual 81Kr atoms. In this method, a vacuum ultraviolet beam was used to resonantly excite krypton atoms in order to obtain atomic species selectivity and a small quadrupole mass spectrometer provided isotopic selectivity. After selection, the krypton ions were counted as they were implanted into a target. The method will also work for other isotopes.