Two-photon-excited luminescence of biologically active solid-state structures

A study was made of the characteristics of two-photon-excited luminescence of a number of pharmaceutical and biologically active solid-state materials: aspirin, sulfadimethoxine, Streptocid (sulfanilamide), pig insulin, and lysozyme. This luminescence was excited by pulse-periodic laser radiation. The characteristics of the luminescence spectra were compared with the familiar spectra of two-photon-excited luminescence of L-tryptophan. The results were used to determine the characteristics of molecular excitons in the investigated organic crystals and to estimate the concentration of tryptophan in solid-state proteins.