A smog chamber for studies of the photochemical degradation of chemicals in the presence of aerosols

Kinetics of the gas-phase reactions of OH radicals with alkanes and cycloalkanes

“…In the temperature range 292-390 K the agreement between the absolute and relative rate studies is good. The room temperature relative rate data of Atkinson et al (1983a), , Behnke et al (1987Behnke et al ( , 1988 and McLoughlin et al (1993), which are not shown in the Arrhenius plot in Fig. 11, are also in good agreement with these data of Atkinson et al (1982a), Klein et al (1984), Donahue et al (1998) and DeMore and Bayes (1999).…”

“…The absolute rate studies of Abbatt et al (1990), Talukdar et al (1994) and Donahue et al (1998) are in good agreement at room temperature, and those of Talukdar et al (1994) and agree well over the temperature range common to both studies (300-370 K). However, rate constants derived from the relative rate studies of Atkinson et al (1982b), Behnke et al (1987Behnke et al ( , 1988, Harris and Kerr (1988), Donaghy et al (1993) and DeMore and Bayes (1999) are consistently ∼10% lower that the absolute rate constants. Figure 9 shows an Arrhenius plot of the absolute rate constants of Abbatt et al (1990), Talukdar et al (1994) and Donahue et al (1998) together with the relative rate data of Baldwin and Walker (1979), Atkinson et al (1982b), Harris and Kerr (1988) and DeMore and Bayes (1999).…”

“…However, for the >C 3 alkanes and for the cycloalkanes, rate constants obtained from relative rate studies are an important part of the data-base (and in some cases are the only data available), and the recommendations then use a combination of absolute and relative rate data. As shown in Table 3, for a series of C 3 -C 10 n-alkanes and cyclohexane at room temperature the relative rate studies of Atkinson et al (1982a, b), Benhke et al (1987Benhke et al ( , 1988, and DeMore and Bayes (1999) are in generally excellent agreement, and these relative rate studies severely a Based on the data cited in the table from the studies of Atkinson et al (1982b), Behnke et al (1987Behnke et al ( , 1988 and DeMore and Bayes (1999). There are a number of alkanes for which the OH radical reaction rate constants have been measured relative to those for the reactions of OH radicals with H 2 or CO, often at elevated temperatures.…”

“…As shown in Table 33, the database for this reaction is small, with the only absolute rate study being that Koffend and Cohen (1996) at 1086 K (note that, assuming that the experimental data listed in their Table III is correct, then the temperature is incorrectly stated in both the abstract and Table VII of Koffend and Cohen (1996) ( Atkinson et al, 1982b;Klöpffer et al, 1986;Behnke et al, 1987Behnke et al, , 1988Ferrari et al, 1996). A least-squares analysis of the rate constants from the studies of Atkinson et al (1982b), Behnke et al (1987Behnke et al ( , 1988, Koffend and Cohen (1996) and Ferrari et al (1996), using the expression k=AT 2 e −B/T , leads to the recommendation of k(n−heptane)=1.95×10 −17 T 2 e 406/T cm 3 molecule −1 s −1 over the temperature range 290-1090 K, and k(n−heptane)=6.76×10 −12 cm 3 molecule −1 s −1 at 298 K, with an estimated overall uncertainty at 298 K of ±20%.…”

“…A least-squares analysis of the rate constants from the studies of Atkinson et al (1982b), Behnke et al (1987Behnke et al ( , 1988, Koffend and Cohen (1996) and Ferrari et al (1996), using the expression k=AT 2 e −B/T , leads to the recommendation of k(n−heptane)=1.95×10 −17 T 2 e 406/T cm 3 molecule −1 s −1 over the temperature range 290-1090 K, and k(n−heptane)=6.76×10 −12 cm 3 molecule −1 s −1 at 298 K, with an estimated overall uncertainty at 298 K of ±20%.…”