Theory
Base is added to a solution of luminol in order to deprotonate
the NH (secondary amine) groups so that the dianion of the compound
may be formed. The addition of bleach to the solution causes
the oxidation of luminol, which results in the production of
the excited state of the 3-aminophthalate molecule. The decay
of this excited state molecule to the ground state causes the
release of a photon. This release is the observed "chemiluminescence"