I want to pump energy into a chemical species to increase its reaction cross section with another. Typically these species react upon collision when their relative kinetic energy exceeds the activation energy. I want to find a way to increase the reaction rate for interactions at slower relative kinetic energies. I am imagining pumping the mixture with EM radiation at a frequency that is strongly absorbed by one of the species but I am not sure how to figure out what that frequency is, how much energy would be needed, or if this would even work! How should I go about investigating this? Is this possible? What things about the chemical species do I need to know to answer my question about frequency and energy?