OBSERVATION OF THERMAL ELECTRON DETACHMENT FROM CYCLO-C4F8- IN FALP EXPERIMENTS

The methodology for use of a flowing afterglow-Langmuir probe apparatu s to measure thermal electron detachment rate coefficients is describe d. We determined the thermal detachment rate coefficient (1010 +/- 300 s-1) for cyclo-C4F8- ions and the rate coefficient (1.6 +/- 0.5 x 10( -8) cm3 s-1) for electron attachment of cyclo-C4F8 at 375 K. The sole ionic product of attachment is cyclo-C4F8-. The equilibrium constant f or the attachment/detachment reaction yields a free energy for attachm ent at 375 K of -0.63 +/- 0.02 eV, from which we estimate the electron affinity (0 K value) of cyclo-C4F8 to be about 0.63 eV.