The Spectra of the Chemiluminescence, Fluorescence and Absorption of Lucigenin and Its Electron Spin Resonance

Abstract

Abstract In order to study the mechanism of the chemiluminescence of lucigenin which was emitted with hydrogen peroxide in an alkaline solution, the color and the spectrum of the chemiluminescence and fluorescence, the spectrum of absorption, and the electron spin resonance were investigated. The color of the chemiluminescence was found to vary from green to blue with a decrease in the concentration of lucigenin. The spectrum of the blue chemiluminescence spread over only a visible region of 420—650 m/μ, with a peak at 485 mμ. With an increase in the concentration of lucigenin, the peak shifted to 510 m/μ or longer, corresponding to the green color of the chemiluminescence. This shift is due to self-absorption by lucigenin. The fluorescence spectrum of lucigenin in aqueous sodium hydroxide showed a peak at 508 mμ. The peak gradually disappeared, and the spectrum eventually showed new peaks at 435 and 450 m/μ which almost agreed with the peaks of the fluorescence spectrum of 10-methylacridone. Lucigenin exhibited an electron spin resonance of a single peak (g-value 2.004) in a solid state. These results show that the chemiluminescence of lucigenin is neither of the fluorescence of lucigenin nor that of 10-methylacridone yielded in the chemiluminescent solution of lucigenin and that the mechanism of the chemiluminescence is likely to involve a free radical intermediate.