01/02/2007 - Postdoctoral position - Yale University

We will characterize charge transfer molecules and organic conductors in new ways. Advances in supramolecular chemistry, self-assembly, single molecule phenomena, and electron transfer phenomena have extended charge transfer studies far beyond typical homogeneous media. We propose THz absorption and emission experiments to obtain information not obtainable with any other method. Membranes, Langmuir-Blodgett (LB) films, and self-assembled monolayers (SAMs) are all amenable to THz studies. Membranes are important due to their obvious connection with biological systems, while LB films and SAMs allow a greater amount of control over the constituent species and chemical functionality. Of these, SAMs provide the greatest amount of flexibility in molecules studied as well as the possibility of building and probing more complicated SAM heterostructures. They have served as model systems of more complex environments. For example, the intermolecular interaction among molecules of interest in the field of molecular electronics can be investigated. THz emission spectroscopy captures the THz pulse emitted when a collection of molecules in a crystal, in a film or monolayer, or oriented in solution, are photoexcited thereby changing the net polarization of the sample. This differs from the other types of THz studies in that a THz generator is not needed, only a detector, since the sample itself generates the THz pulse. With THz emission spectroscopy, it is possible to characterize intramolecular and intermolecular charge transfer in molecules and ordered assemblies of molecules. The change in polarization of the sample generates the signal, and no other secondary process need be monitored. Molecular conductivity is best studied with THz absorption spectroscopy, although it will influence THz emission as well.