A value of (6 f 1 j X 1O-34 cm6 molecule-2 s-' has been obtained for the room tcmperoture rate constant of the homogeneous recombination of fluorine atoms with He as the third body.
Recently Ganguli and Kaufman
[ 1) determined the recombination rate of F atoms using a Cl;! titration tcchniquz. Their rate constant is about a factor of 100 lower than the accepted values for other atom recombination .eactions. Recombination rates for F atoms calculated from shock tube dissociation rates and the equilibrium constant, and extrapolated to room temperature range from 102' to 1Q3s cm6 mo-leculee2 s-1 '+. The main re:lson I^,?r t!le spread is the uncertainty in the tempcra'ure coefficient of the dissociation rate constant. During a study rJf the ESR spectrum of aiomic F [3], considerable data on homogetleous and surface recombination were obtained. The recombina::ion reactions were measured with a quart; faqt flow system. F atoms were produced in a microwave discharge with an Evenson type 2450 MHz cavity 141. The discharge section of the flow system consisted of a doublewalltd quartz tube with fluorocarbon oil maintained sligh*.ly below room temperature, circulating through the outer jacket. Earlier experiments without cooling and with other cavities invariably led to erosion of the quartz in the discharge zone resulting in intense 02 and 0 spectra. The desired fluorine-atom concentrations were obtained with microwave power absorptions from 5 to 15 W. Atom concentrations along the length of the flow tube were determined by electron spin resonance spectroscopy. * A review of the fluorine dissociation and recombination rates ha:. been given by Lloyd [2].