Abstract

Coulomb explosions of benzene induced by an intense femtosecond laser field were examined in the present study by time-of-flight (TOF) mass spectrometry at laser intensities of 8.0 × 10¹⁶ W cm⁻², with a pulse width of 120 fs. The multiply charged ions of C^q+ (q = 1~4) and H⁺ were detected and their energies were determined to be distributed in the range of 0 ~ 120 eV. The explosions were concluded to be anisotropic because the kinetic energies of multiply charged carbon ions are high parallel to the laser electric field. Molecular dynamics (MD) simulations, including the effects of tunnel ionization, electron recombination, and the spatial configuration of benzene for laser electric fields were performed to elucidate the kinetic-energy distributions and explosion dynamics. The simulations suggest that the charge-hopping mechanism enhances ionization, finally leading to an anisotropic explosion. Furthermore, we have found that the time profiles of the hopping greatly depend on the spatial configurations in the case of the benzene.

© 2001 IEEE