Resonant Multiphoton Ionization of H 2 by an ArF Laser and Application to Atmospheric Molecules

Abstract

When a tunable ArF laser beam was focused into a pulsed H2 gas jet, three-photon ionization and gas breakdown were resonantly enhanced at 193.28 nm. The ionization efficiency was calculated using a rate equation model. Based on the results, resonant multiphoton ionization of atmospheric species was discussed, considering the application of this scheme to laser-controlled lightning. N2 molecules can be efficiently ionized at a wavelength of 283.1 nm by a tunable laser. Applying a similar analytical model to N2 allowed the estimation of the laser energy required to form a long (100 m) weakly ionized (1013 cm-3) channel in the atmosphere.