Dissociative ionization of small molecules in intense laser fields

Abstract

With the development of high power, subpicosecond lasers, it has become possible to study the process of multielectron dissociative ionization of small molecules at intensities in excess of 10¹⁴ W cm^-2. At such intensities the conventional multiphoton approach is too complex and the field ionization model becomes more attractive. This article reviews the experimental results obtained to date and indicates how certain aspects of the process, namely the mode of multiple ionization, the thresholds for multiple ionization, the charge symmetry of the fragment ion production and their peaked angular distributions, can be explained in terms of a field ionization, Coulomb explosion model. However, a more sophisticated approach is undoubtedly required to explain the lack of variation of fragment ion kinetic energies with laser risetime, the variation of kinetic energies with laser wavelength and the molecule specificity of the process.