The vibrational spectra of phenol/ammonia clusters (1:2-5) in S-0 and those of their photochemical reaction products, (NH3)(n-1)NH4 (n=2-5), which are generated by excited-state hydrogen transfer, have been measured by UV-IR-UV ion dip spectroscopy. The geometries, IR spectra and normal modes of phenol-(NH3)(n) (n=1-5) have been examined by ab initio molecular orbital calculations, at the second-order Moller-Plesset perturbation theory level with large basis sets. For the n=2 and 3 reaction products, similar vibrational analyses have been carried out. From the geometrical information of reactants and products, it has been suggested that the reaction products have memories of the reactant's structure, which we call "memory effect."