Light quenching of fluorescence of aromatic amino acids

This paper presents the results of investigation of light quenching of fluorescence of molecules of aromatic amino acids. Radiation of the fourth harmonic (270 nm) of an yttrium orthoaluminate-neodymium laser was used to excite fluorescence. The third harmonic of the same laser (360 nm) was used as quenching radiation. Aqueous solutions of tryptophan, tyrosine, and phenylalanine were investigated at pH 6. The light quenching of fluorescence can serve as a method for determination of the efficiency of two-step photochemical reactions under UV irradiation of organic molecules.