Mass spectrometric implications of high-pressure ion sources

The nature of supersonic free jet expansion of a gas from high pressure into vacuum is reviewed and characterized in this article. The increasingly widespread applications and implications of this jet expansion process in mass spectrometry are described. Particular attention is paid to prospective advantages and possible problems when such jets are used to transport ions from a source at high pressure into the vacuum environment of a mass analyzer. (C) 2000 Elsevier Science B.V.