Mass spectra of ethylene in intense laser fields

We experimentally studied the pulse duration effects on the mass spectra of ethylene in intense laser fields. At an intensity of 1.3×1014W/cm2, parent ions C2H4+ are dominant for both 6.4fs and 110fs laser pulses. However, strong H+ ion signal is observed only in the 110fs laser pulse. It is absent in the 6.4fs laser pulse. When the laser intensity is 6.2×1014W/cm2, singly and doubly charged parent ions are observed for both 6.4fs and 110fs laser pulses. In addition, some highly charged carbon ions are present for 110fs laser pulses. However, these highly charged carbon ions are replaced by some other singly and doubly charged fragmental ions for 6.4fs laser pulses. The above different mass spectra for ethylene are explained by the nuclear motion assisted by the strong laser fields with different pulse durations.