ATMOSPHERIC CHEMISTRY OF HFC-236CB - SPECTROKINETIC INVESTIGATION OF THE CF3CF2CFHO2 RADICAL, ITS REACTION WITH NO AND NO2, AND THE FATE OFTHE CF3CF2CFHO RADICAL
Te. Mogelberg et al., ATMOSPHERIC CHEMISTRY OF HFC-236CB - SPECTROKINETIC INVESTIGATION OF THE CF3CF2CFHO2 RADICAL, ITS REACTION WITH NO AND NO2, AND THE FATE OFTHE CF3CF2CFHO RADICAL, Journal of physical chemistry, 99(48), 1995, pp. 17386-17393
A pulse radiolysis technique was used to study the UV absorption spect
rum of CF3CF2CFHO2 radicals (at 250 nm sigma = (175 +/- 36) x 10(-20)
cm(2) molecule(-1)). The observed bimolecular rate constant for the se
lf reaction of CF3CF2CFHO2 radicals was k(13obs) = (5.2 +/- 1.4) x 10(
-12) cm(3) molecule(-1) s(-1). Rate constants for reactions of CF3CF2C
FHO2 radicals with NO and NO2 were k(3) > 8 x 10(-12) and k(4) = (6.3
+/- 0.7) x 10(-12) cm(3) molecule(-1) s(-1), respectively. Using a FTI
R spectrometer/smog chamber technique it was shown that, under atmosph
eric conditions, reaction with O-2 and decomposition via C-C bond scis
sion are competing loss mechanisms for CF3CF2CFHO radicals. A lower li
mit of 10(5) s(-1) was deduced for the rate of decomposition of CF3CF2
CFHO radicals via C-C bond scission at 296 K in 1 bar of SF6 diluent.
It is estimated that in the atmosphere approximately 98% of CF3CF2CFHO
radicals will undergo decomposition into C2F5 radicals and HC(O)F and
2% will react with O-2 to give C2F5C(O)F. As part of this work relati
ve rate methods were used to measure rate constants of(1.3 +/- 0.3) x
10(-12) and (1.5 +/- 0.3) x 10(-15) cm(3) molecule(-1) s(-1) for the r
eactions of CF3CF2CFH2 with F and Cl atoms, respectively.