Coulomb explosion of benzene irradiated by an intense femtosecond laser pulse

A Coulomb explosion in a benzene molecule induced by an intense femtosecond laser field has been studied using the method of time-of-flight mass spectrometry. The laser intensity region of a Ti:sapphire laser was from 2.9×1016 to 1.8×1017 W cm−2. Major ions were found to be multiply-charged carbon atoms, while the ion intensities of benzene fragments were small. The initial kinetic energy releases of Cq+ (q=1∼4) ions increased with increases in laser intensity, reaching 330 eV for the C4+ ion at 1.8×1017 W cm−2. A critical structure of the Coulomb explosion, where the charges are non-uniformly distributed and the structures are expanded slightly, has been postulated to explain such great energies of the multiply-charged ions.