No abstract

The pulse laser photolysis/laser induced fluorescence (PLP-LIF) technique has been used to measure the rate constants of the reactions of OH radicals with dimethyl ether and methyl-tert-butyl ether. OH radicals were produced by photolysis of H 2 O 2 at λ ) 266 nm. The photolysis cell was heated by a small electric furnaces in order to obtain information on the temperature dependency of the rate constants in the domain of 295-660 K. A preliminary study of the reaction of OH with methane was carried out to control the experimental setup. The Arrhenius expression obtained in the temperature range of 295-668 K, k OH+CH 4 ) (5.65 ( 0.49) × 10 -21 T 3.01 exp[-(959 ( 36)/T], is in very good agreement with previous determinations (bimolecular rate constant units: cm 3 molecule -1 s -1 ; error limits ( 2σ). For the reactions of OH with ethers, the Arrhenius expressions derived from our own results are k OH+DME (295-618 K) ) (3.02 ( 0.10) × 10 -20 T 2.85 exp[(618 ( 13)/T] and k OH+MTBE (297-616 K) ) (6.59 ( 0.43) × 10 -19 T 2.40 exp ([(499 ( 22)/T]. Combining these data with those from previous experimental studies allows us to derive Arrhenius expressions in larger temperature domains: k OH+DME (230-650 K) ) (4.59 ( 0.21) × 10 -19 T 2.46 exp[(476 ( 14)/T] and k OH+MTBE (230-750 K) ) (1.58 ( 0.09) × 10 -20 T 2.93 exp([(716 ( 18)/T].