More detailed description of special area of interest is on the right. Utilizing steady-state spectroscopy as well as ultra-fast time-resolved fluorescence (Upconversion) and absorption (pump-probe) measurements our research is focused on probing the kinetics of the fast energy redistribution processes that occur in branched (and related) macromolecular structures. With the additional use of fluorescence anisotropy decay measurements, we have characterized the fundamental limits of interaction in different molecular architectures. Investigations of novel larger branched structures (obtained through collaboration) as well as more fundamental investigations (were the synthesis of model compounds is carried in our lab) are used to probe the important structure-function relationships in these systems. These investigators are coupled with measurements of interactions and electronic dephasing in the branched (aggregate) systems with 3-pulse photon echo spectroscopy (3PEPS). This combined approach allows for the analysis of the energy transfer, interaction strength, dephasing, as well as other important physical properties of particular macromolecular systems.

The research in the group is also directed at the use of organic branched structures for applications in nonlinear optics as well as quantum optical and quantum interference effects. The investigations of strong interactions in particular multi-chromophore systems suggest that there is a possibility of enhanced transition dipole moments. This has been observed in organic branched structures in our laboratory. New methods, both synthetically and optically to enhance the nonlinear response of organic branched macromolecules are developed in this research effort. These measurements are combined with two-photon-emission and degenerate-four-wave mixing experiments to fully characterize the complete response of novel materials.

The initial investigations utilizing organic materials in quantum optical phenomena were carried out in our laboratory. This included measurements of photon number squeezed states of light in an organic polymeric material. The ability to reduce the photon fluctuation below the shot-wave limit is of significant use to those interested in an all optical telecommunication system. The striking result was that the organic material gave rise to the same magnitude of ” squeezed light” as was observed for inorganic systems with interactions lengths that was orders of magnitude longer. Our recent investigations in this area include measurements of entangled photon and their use in the spectroscopy of organic materials at low photon-number as well as other novel quantum interference effects with organic materials.

by Dr. Theodore Goodson III