Fluorescence of Chlorophyll a in Monolayers

Abstract

An apparatus has been constructed which permits observation of the fluorescence of pigment molecules spread in monomolecular films on aqueous surfaces. It is found that while the emission from pure chlorophyll films is strongly concentration quenched, relative fluorescence yield increases nearly 1000‐fold when the chromophores are effectively separated by a two‐dimensional diluent. Factors affecting the efficacy of several diluents are discussed. The emission spectrum of diluted chlorophyll a monolayers is presented. Measurements of relative yield as a function of pigment concentration in mixed films containing chlorophyll and oleyl alcohol are consistent with a model involving energy migration to nonfluorescent centers in the monolayer. The present results, however, cannot demonstrate the quantitative validity of any specific mechanism for the migration process.