AN EXPERIMENTAL AND THEORETICAL-STUDY OF THE DISSOCIATIVE IONIZATION OF CCL4, CHCL3 AND CH2CL2 BY AN INTENSE LASER FIELD

The dissociative ionization of polyatomic molecules CCl4 (tetrachlorom ethane), CHCl3 (trichloromethane) and CH2Cl2 (dichloromethane) by inte nse, 532 nm, 35 ps, 10(13) W cm(-2) linearly polarized, laser fields i s explored. The laser-induced fragmentation pattern is found to be sub stantially different from that obtained using 70 eV electrons. Attempt s are made to rationalize these differences in terms of distortions of the molecular electron density distributions caused by the intense la ser field. Such distorted charge-cloud distributions are computed in a n approximate fashion by ab initio quantum-chemical techniques. Angula r distributions of various fragment ions have also been measured. A pr onounced anisotropy is exhibited in many (but not all) cases, with the ion signal being detected mainly along the direction of the laser's p olarization axis.