Angular distributions of fragment ions in dissociative ionization of CH2I2 molecules in intense laser fields

摘要

The interaction of CH2I2 with a 90 fs 800 nm or 400 nm linearly polarized laser field in the intensity range from 1 x 10(14) to 1.4 x 10(15) W cm(-2) was studied by means of a time-of-flight mass spectrometer. Extensive fragmentation was observed at both wavelengths. The kinetic energy released in the Coulomb explosion was obtained by the peak splitting method. The angular distributions were determined for various fragment ions. It was found that the multiple charged iodine ions exhibit a markedly anisotropic distribution, while single charged fragments result a nearly isotropic angular distribution. It has been inferred that the strongly anisotropic angular recoil distributions of multiple charged fragment ions are due to geometric alignment.