Data obtained with the HT-FALP apparatus for at 495 K in a He/Ar buffer gas vs reaction time . The diffusion data were obtained in the absence of the . The solid curves are solutions of rate equations using . represents molecular cations produced in reaction with (and some ). The reaction rate was taken to be , and the electron recombination rate constant was estimated at at 495 K.
Comparison of the present data (AFRL) with those of Boston College (BC, Ref. 16), Birmingham University (B’ham, Ref. 11), and Oak Ridge National Laboratory (ORNL, Ref. 14, extrapolated to thermal energy in the present work). Off scale are Rennes data (Ref. 16) at temperatures of .
Temperature dependence of halomethane electron attachment rate constants. Solid circles are the present (AFRL) data. The other data showing temperature dependences are those of Birmingham University (Ref. 11), except for (at 300, 400, and 500 K) which are from ORNL (Ref. 14). The points shown only at 300 K are all ORNL data (Ref. 20). The datum is likely in error (see text).
Correlation of 300 K electron attachment rate constants (yielding ion product) with reaction exothermicity (a negative value implying endothermicity). The lines are drawn to guide the eyes for molecules containing no F atoms (right) and molecules with no H atoms (left). The closed circles are data plotted vs energetics from G3 calculations (Table I). The open points are the same data plotted vs energetics deduced from BDEs minus EA(Cl).
Calculated G3 total energies, adiabatic EAs, and C–Cl BDEs at 0 K for , , , , and dissociation fragments relevant to the energetics of attachment reactions. is included as relevant to comments in the text on endothermic electron attachment to .
Electron attachment rate constants for , , and obtained at temperatures . Data for were given in Ref. 1. The present experimental uncertainty is ±25% except for cases where significant correction for electron-ion recombination was made: If , then the estimated uncertainty is ±35%.
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