Shock tube studies of SF4dissociation have been made in the temperature range 1650ndash;1950deg;K. Rate constants for the initial fragmentation of SF4have been determined from ir measurements and are explainable in terms of classical unimolecular reaction kinetics. The data were correlated with the Ricendash;Ramspergerndash;Kassel (RRK) theory; the values used were 79.0 kcal/mole for the SF3sngbnd;F bond strength, 1013.63secminus;1for the prehyphen;exponentialAfactor,lgr;Dsgr;m2thinsp;equals;thinsp;5.79thinsp;times;thinsp;10minus;16cm2, andSthinsp;equals;thinsp;6. Kinetic rates obtained from exponentially decaying radiation at 12.6mgr;and temperatures of 2050ndash;2800deg;K are attributed to SF3and lie near the lowhyphen;pressure limit of unimolecular reactions. The SF3dissociation rates can be described bykthinsp;equals;thinsp;4.29thinsp;times;thinsp;1015explpar;minus;thinsp;71.8thinsp;sol;thinsp;RTrpar;ccsol;molemiddot;sec, whereRis in kilocalories per molemiddot;degree Kelvin.
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