Reaction between OH and HCHO:temperature dependent rate coefficients (202-399 K) and product pathways (298 K)

摘要

Absolute rate coefficients for the title reaction,OH+HCHO->products (R1) were measured over the temperature range 202-399 K using the technique of pulsed laser photolytic generation of OH radical coupled to detection by pulsed laser induced fluorescence.The accuracy of the rate constants obtained was enhanced by on-line optical absorption measurements of the formaldehyde concentration.The temperature dependence of the rate coefficient is given by:k_1(202-399 K)=9.52X10~(-18)T~(2.03) exp{636/T} cm~3 molecule~(-1) s~(-1) with the rate coefficient at room temperature of 8.46X10~(-12) cm~3 molecule~(-1) s~(-1).The estimated total error (95% confidence) associated with the rate coefficient derived from this expression is estimated at 5% close to 300 K,increasing to 7% at the extremes of the temperature range covered.The present results,which extend the database on this reaction to cover temperatures relevant for the upper troposphere,are compared to previously published measurements,and values of k_1 for atmospheric modelling are recommended.In accord with most previous studies,we find no evidence for H atom formation in (R1).