MECHANISMS FOR ION FORMATION IN GAS-PHASE

Ion formation in gas phase involves various mechanisms, depending on: the excitation process (electronic bombardment, photoabsorption ... ) the primary mechanism (direct ionization, resonant state formation followed by autoionization, hole formation followed by Auger effect), the competing processes (multielectron ionization, multiphoton ionization, dissociation). These various mechanisms and the main detection techniques are presented, as an introduction to more specialized articles. The theoretical methods used for ionization calculations are briefly described. Finally, recent developments and perspective in this domain are discussed (use of ultra-fast and/or ultra-intense laser pulses, pump-probe techniques, combination of laser and synchrotron radiations).