Effects of argon on the IR multiphoton dissociation of C3F6

This work reports on the infrared multiphoton dissociation of hexafluoropropene (0 to 2 mbar) in the presence of added argon (0 to 15 mbar), at a constant value of the irradiation fluence (4 J cm(-2)). Together with the quenching of the dissociation yield, the addition of Ar produces a modification of the qualitative behaviour of C3F6 with respect to the dissociation process, associated with the induction of an anharmonic barrier similar to that induced by varying the irradiation fluence. This effect is observed through the activating role of C3F6-C3F6 collisions found at higher Ar pressures. The anharmonic barrier is principally vibrational, although for small values of fluence a rotational component has been detected. (C) 1997 Elsevier Science B.V.