Cooperative effects in nonlinear optical spectroscopy of J-aggregates

Abstract

J‐aggregates of polymethine dyes (for structure and spectrum see Figure 1) have become a focus of interest in the interdisciplinary field of molecular nonlinear optics [1–5] and Langmuir‐Blodgett engineering [6]. Polymethine dye J‐aggregates were formed in LB layers, and storage of optical information in monolayers and mixed multilayers has been recently demonstrated [7]. Sharp and intense absorption bands at room temperature provide the possibility of recording optical information by using the photoablative technique [8] or photodissociation [9,10] (photodesordering) of J‐aggregates. Although the multicolour information storage devices exploit intense and narrow absorption bands of aggregates, the physical mechanism of storage is mostly thermal change in steady‐state spectral characteristics.