An in-depth study of the effects of functional group substitution on benzene's electron-ion dissociative recombination (e-IDR) rate constants has been conducted. The e-IDR rate constants for nitrobenzene, benzonitrile, acetophenone, benzyl methyl ether, and phenyl isothiocyanate have been measured using a flowing afterglow equipped with an electrostatic Langmuir probe (FALP). A trend has been indicated between the associated positive Hammett σpara constant for each functional group substitution and the e-IDR rate constants for the protonated form of the benzene analog. Such a plot has indicated that protonated benzene analogs which have functional groups substitutions with a positive Hammett σpara constant value have approximately the same e-IDR rate constant of 4.6 × 10-7 cm3 s-1. Implications of the observed trends to the predictions of e-IDR rate constants for unmeasured benzene analogs are discussed.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the support of NASA under Grant NNX10AB96G . We would also like to thank Inbal Tuvi-Arad from The Open University of Israel for her help and suggestions.
- Benzene analog
- Electron-ion dissociative recombination
- Flowing afterglow
- Hammett constant