NEW PHENOMENA IN THE SPECTROSCOPY OF DYE AGGREGATES

Abstract

Ionic dyes form aggregates with some well-known properties at the two extermes of low and high degree of association. The behavior of the lifetime of the triplet state of a cyanine dye at the lower limit of aggregation will be discussed. Both cation-cation and cation-anion interactions seem to be evident. At a high degree of aggregation or when a complex is formed with an optically active salt or polymer, a dye may show induced optical activity at the position of the absorption bands of the (inherently inactive) dye. New aspects of this phenomenon will be described.