ATMOSPHERIC CHEMISTRY OF HFC-236FA - SPECTROKINETIC INVESTIGATION OF THE CF3CHO2-CENTER-DOT-CF3 RADICAL, ITS REACTION WITH NO, AND THE FATEOF THE CF3CHO-CENTER-DOT-CF3 RADICAL

A pulse radiolysis technique was used to investigate the UV absorption spectrum of (CF3CHO2CF3)-C-. over the wavelength range 220-290 nm. At 250 nm the absorption cross section for (CF3CHO2CF3)-C-. was sigma (1 86 +/- 27) x 10(-20) cm(3) molecule(-1). The rate constant for the sel f-reaction rate of (CF3CHO2CF3)-C-. was determined to be (5.6 +/- 0.7) x 10(-12) cm(3) molecule(-1) s(-1). By following the increase in NO2 at 400 nm, the rate constant for the reaction of (CF3CHO2CF3)-C-. with NO was found to be (1.1 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1). The reaction of (CF3CHO2CF3)-C-. with NO gives (CF3CHOCF3)-C-.. A Four ier transform infrared technique was used-to show that in the atmosphe re >99% of (CF3CHOCF3)-C-. react with O-2 to give CF3COCF3. The atmosp heric fate of CF3COCF3 is photolysis or incorporation into rain-cloud- sea water followed by rapid hydrolysis. As part of the present work re lative rate techniques were used to measure rate constants at 295 +/- 2 K for the reactions of Cl and F atoms with CF3CH2CF3 of <8 x 10(-17) and (1.8 +/- 0.4) x 10(-13) cm(3) molecule(-1) s(-1) respectively. In addition, the rate constant for reaction of F atoms with (CF3)(2)CHOH was determined to be (3.5 +/- 1.1) x 10(-12) cm(3) molecule(-1) s(-1) . All experiments were performed at 296 +/- 2 K.