How temperature affects the stereoisomerization variations of the optical properties of solutions of polymethine dyes

摘要

The influence of temperature on the absorption and fluorescence properties of solutions of dicarbocyanine dyes and on stereoisomerization processes is studied in the range from -60 to 60 degrees C. It is shown that the optical density and the absorption spectrum vary as a result of temperature redistribution of the concentration of four stereoisomeric forms. The fluorescence-intensity variations are determined by variations of both the concentration of the isomers and the quenching rates associated with photoisomerization of the molecules in the excited state. It is concluded that recording the changes of the optical density and fluorescence intensity makes it possible to investigate the temperature distribution in a solution. It is shown that the fluorescence technique of investigation is several times more sensitive than the absorption technique. (C) 2006 Optical Society of America.