Production of Hydroxyl Radicals in the Dark

Oxidation is prevalent in atmospheric chemistry due to the abundance of oxidants in the atmosphere. One of the commonly found oxidants is hydroxyl (OH) radical. Previously, OH radicals have been generated by means of UV photolysis, but the concurrent presence of photolysis and oxidation makes it challenging to pinpoint the exact mechanism behind the reactions occurring in the environmental chamber. Thus, a method for the production of OH radicals in a dark environment would be highly beneficial for decoupling the OH radical initiated-oxidation chemistry from photolysis. A method involving the ozonolysis of 2,3-dimethyl-2-butene (tetramethylethylene, TME) has been proposed by researchers from Center for Atmospheric Particle Studies in Carnegie Mellon University. We further investigated the feasibility of TME ozonolysis as a dependable source of OH radicals in a dark environment. Using the TME + O3 method, we estimated the produced OH concentrations to be approximately 107~108 molecules cm-3.