We investigated the title reaction at collision energy 3.5 kcal mol(-1) in a crossed molecular beam apparatus using undulator radiation as an ionization source. Time-of-flight (TOF) spectra of product C3H3 were measured in laboratory angles from 20 degrees to 100 degrees using two photoionization energies 9.5 and 11.6 eV. These two sets of experimental data exhibit almost the same TOF distributions and laboratory angular distributions. From the best simulation, seven angler specific kinetic-energy distributions and a nearly isotropic angular distribution are derived for product channel C3H3 + H that has an average kinetic-energy release of 15.5 kcal mol(-1), corresponding to an average internal energy of 33.3 kcal mol(-1) in C3H3. Furthermore, TOF spectra of product C3H3 were measured at laboratory angle 52 degrees with ionizing photon energies from 7 to 12 eV. The appearance of TOF spectra remains almost the same, indicating that a species exclusively contributes to product C3H3; the species is identified as H2CCCH (propargyl) based on the ionization energy of 8.6 +/- 0.2 eV and the maximal kinetic energy release of 49 kcal mol(-1). Theoretical calculations indicate that the rapid inversion mechanism and rotation in intermediate H2CCCH2 can result in a forward-backward symmetric angular distribution for product C3H3 + H. The present work avoids the interference of reactions of C(D-1) and C-2 radicals with C2H4 and rules out the probability of production of other isomers like c-C3H3 and H3CCC proposed in the previous work at least at the investigated collision energy.