Ion-optical properties of time-of-flight mass spectrometers

The time focusing properties of time-of-flight mass spectrometers in current use, under development, or with probable future applications are presented. For most of the presented analyzer types a mass resolution formula was given to calculate instrumental performance. These formulas account for second or third order contributions to the ion packet length, depending upon the analyzer's focusing degree. This analysis covers homogeneous electric field mirrors, cylindrical reflectrons, quadratic potential mirrors with and without field free spaces included, linear drift space focusing analyzers, as well as quadrupole trap time-of-flight hybrid systems. The velocity focusing procedures by delayed extraction and postsource focusing, very useful in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, are also detailed. (Int J Mass Spectrom 206 (2001) 211-229) (C) 2001 Elsevier Science B.V.