Mechanism and Product Energy Disposal in the Reaction of Ar(1+)(2P3/2) with CS2(X1Σg(+)

Article abstract of DOI:10.1021/j100326a011

The reaction of Ar(1+) with CS2 is investigated at thermal and near thermal energies by using both tandem ion cyclotron resonance (ICR) spectroscopy and kinetic energy ICR.At thermal energies the absolute rate constant is measured to be 2.9*10^-10 cm³/s, and the ionic product branching ratio to be 97 percent S(1+) and 3 percent CS2(1+).Kinetic energy studies revealed the CS2(1+) product is 90 percent formed in the A<*>2Π state with a near Franck-Condon vibrational state distribution and 10 percent in the X<*>2Π state.The S(1+) product is formed exclusively in the ground S(1+)(4S) state with the maximum kinetic energy allowed by energy and momentum conservation.The implication is the originating Ar(1+)/CS2 charge transfer takes place via a long-range electron jump since no momentum transfer occurs (in contrast to the formation of CS2(1+) (A<*>2Π), where substantial momentum trasfer occurs).These data strongly suggest the S(1+)(4S) product arises from nascent CS2(1+)(B<*>2Σ_u(+)) that is rapidly predissociated by the 4Σ-state that leads to S(1+)(4S)/CS(X1Σ(+)) products.The crossing of the two states must occur very near the recombination energy of Ar(1+) (ca. 15.7 eV).This interpretation is consistent with known CS2(1+)(B<*>2Σ_u(+)) radiative lifetimes and theoretical spin-orbit induced coupling between similar states in CO2(1+).The data and interpretations are compared to those in the literature where available.