MULTIELECTRON DISSOCIATIVE IONIZATION OF O-2 IN AN INTENSE PICOSECOND LASER FIELD

The multielectron dissociative ionization of O2 has been studied using an intense picosecond laser at 610 and 305 nm in the 10(13) - 10(15) W/cm2 laser intensity range. The excitation mechanisms producing multicharged dissociating molecular ions are determined from the kinetic energies and laser-intensity dependences of the atomic oxygen ions following the fragmentation of the molecule. Both at 305 and 610 nm, the multicharged atomic fragments (O+,O2+,O3+,O4+) are produced from parent molecular ions that are sequentially ionized as they dissociate. Moreover, the transitions occur at well-defined internuclear distances independent of the peak laser intensity. A comparison with previous results obtained on N2 and CO is discussed.