The mechanisms and kinetics of the photochemistry of organic reaction intermediates have been examined using two—laser excitation techniques, and are illustrated using examples involving naphthalene chromophores. For example, excited 1—naphthylmethyl radicals are excellent electron donors, but not very good acceptors. They abstract halogens efficiently and interact with oxygen 5.5 times faster than their ground state. Other examples include the triplet states of 1,3—dinaph— thyipropanone, 1,2—dinaphthylethane and acenaphthene.