Wide dispersion multiple collector isotope ratio mass spectrometer

A new design for an enhanced dispersion thermal ionization multi-collector isotope ratio mass spectrometer is proposed and the results of tests with a small-scale prototype instrument are presented. The measured performance of the small-scale prototype sized for 6Li and 7Li is compared with the predictions of an ion optical model. The ion optical model is shown to accurately predict the measured mass dispersion, mass resolution, and general ion beam profile, providing confidence that the ion optical modeling can be applied to design of a full-scale instrument. The design concept includes a single magnetic sector and an electrostatic dispersion lens to magnify the mass dispersion so that full sized discrete dynode electron multipliers can be used to simultaneously monitor each isotope. A conceptual model is presented for a thermal ionization instrument capable of simultaneous measurement of seven isotopes in the 240 Da mass range with full size discrete dynode electron multipliers.