Fundamental studies of the plasma extraction and ion beam formation processes in inductively coupled plasma mass spectrometry.

摘要

The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, skimming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced.;The plasma extraction process in ICP-MS was investigated by Langmuir measurements in the region between the skimmer and first ion lens. Electron temperature (T;Axially resolved distributions of electron number density and electron temperature were obtained to characterize the ion beam at a variety of plasma operating conditions. The electron density dropped by a factor of 10;The measured floating voltages (V