Intense Femtosecond Laser Field-Induced Coulomb Fragmentation of C2H4

The fragments from Coulomb explosion of C2H4 irradiated by 130fs laser pulses at 810nm wavelength and intensity around 1015W/cm2 are studied by using a time-of-flight mass spectrometer. The angular distributions of atomic ions exhibit anisotropy with the maximum along the laser polarization axis and the minimum perpendicular to it. The similar full width values at half maximum of angular distributions for Cm+ (m=1–3) ions imply a geometric alignment. On the other side, the singly and doubly charged molecular ions exhibit a markedly isotopic distribution. The dependence of the doubly charged parent ion (C2H4)2+ on laser intensity indicates a nonsequential ionization mechanism.