“…For the system involving ethylene, pulsed CMB studies at E c = 6 kcal mol À1 and 3 kcal mol À1 with VUV photoionization detection 93,94 revealed that the contribution of O( 1 D) cannot be neglected and its role was also confirmed in the CMB experiment performed at E c = 35.1 kJ mol À1 by our research group. 90 The second reason is that the system involving atomic oxygen and cyanoacetylene 91 as reference because the two systems, having a comparable entrance potential energy barrier on the triplet PES and having been studied at nearly equal collision energy, have been investigated by using an oxygen beam generated under the same conditions (in the experimental study of the O( 3 P, 1 D) + ethylene reactions the diameter of the nozzle was different) and because the reaction pathway under analysis is the same, i.e., a CO-forming channel (in the experiment involving ethylene, however, the CO-forming channel was not observed to occur 90,93,94 ). Analyzing the TOF spectra, it should be noted that the fingerprint of the CH 2 CNH + CO channel from the reaction of O( 3 P) and O( 1 D) is clearer at Y = 321 than at the angle Y = 441 (that is, very near to the center of mass angle of 451), because at Y CM the relative contribution of the heavy coproduct of the H-displacement channel (1f) is strongly amplified for kinematic reasons (by the CM -LAB transformation Jacobian 60 ), being scattered over a much narrower LAB angular range (see the Newton diagram in Fig.…”