Optical measurements of ion density in the second vacuum stage of an inductively coupled plasma mass spectrometer

A portion of the ion beam in the second stage of an inductively coupled plasma mass spectrometer was mapped using laser induced fluorescence (LIF). With LIF relative density measurements are made in real time with minimal interference to the ion beam. We report axial measurements of Ba and Sc ion density from 22 to 45 mm behind the tip of the skimmer cone. Additionally, maps of radial ion density with and without Pb and Mg matrices are given for the same two analyte species. The results reveal that earlier ion deposition experiments dramatically underestimated the extent of the radial spread of the ion beam and the influence of matrix on the ion beam. (C) 1998 Elsevier Science B.V.