Abstract: Femtosecond photoeletron imaging technique coupled with time-of-flight mass spectroscopy have been used to study the photoionization/photodissociation mechanisms of allyl chloride with 200 nm, 400 nm and 800 nm femtosecond laser pulses. The results show a wavelength dependent photoionization/photodissociation behavior. It is found that at short wavelength, i.e., 200 nm, two-photon ionization of the parent molecule is the dominant channel, while other fragment ions are generated by dissociation of C3H5Cl+. As we shift to longer wavelength, i.e., 800 nm, dissociation from intermediates states starts to play an important role. Furthermore, the spectra of photoelectron kinetic energy also confirm that photoelectron peaks resulted from the neutral fragments and they are generated from dissociation of the intermediate states of C3H5Cl. This implies that photodissociation starts to play a significant role at longer wavelength since neutral fragments are supposed to be generated on the intermediate states that reached by 400 nm or 800 nm photons.

Key words: femtosecond laser