Ultrafast internal conversion and fragmentation in electronically excited C2H4 and C2H3Cl molecules

The time constants of internal conversion and fragmentation have been determined for ethylene and vinyl chloride excited by 125 fs laser pulses of the wavelength 200 nm. In C2H4 the internal conversion from the lowest excited electronic state to the ground state proceeds within τIC=30±15 fs. In C2H3Cl the internal conversion with τIC=30±10 fs leads to the fast dissociating S1 state (τF=40±10 fs) as well as to the S0 ground state which decays within about 110 ps.