Thermal luminescence spectra of lysine and phenylalanine in O2 measured with a Fourier-transform chemiluminescence spectrometer

A thermal luminescence spectrum of solid lysine in O2 with an emission peak at ∼600 nm was measured at 450 K with a Fourier-transform chemiluminescence spectrometer. No emission bands were observed for lysine in N2, nor its monohydrochloride in O2 or N2, under the same experimental conditions. This observation led us to the conclusion that the intermolecular interaction between the free NH2 group on the side chain of lysine and O2 molecules plays an essential role in this thermal luminescence. This scheme was given support by the finding that the dicyclohexylamine salt of phenylalanine, which has a free NH2 group, but not phenylalanine itself, showed similar thermal luminescence in O2.