Nano-focused multimodal imaging, control, and interaction dynamics: ultrafast spectroscopy reaching the single molecule level

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In this project, funded by the Chemical Measurement and Imaging Program of the Chemistry Division, Professor Markus Raschke and his group at the University of Colorado at Boulder extend ultrafast spectroscopy and coherent control to the nanoscale. Femtosecond plasmonic nanofocusing on a tip will be used to investigate the ultrafast electron dynamics of single quantum systems (molecules, quantum dots) in non-homogeneous environments. Studying the infrared vibrational dynamics and control via optical antenna coupling will push IR spectroscopy to the homogeneous sample size and single molecule limit. Via the demonstration of nanoscale near-field pump-probe and its extension to multidimensional spectroscopy, the group will gain insight into nano-scale charge and energy transfer in thin films of model molecular semiconductors, phase segregated polymers, and device relevant bulk heterojunction materials.Imaging methods that can record details below the conventional resolution limit (~200 nm) are needed to study the interplay between intermolecular coupling and morphology that often dictates the function of important natural and engineered multi-component molecular and nano-materials, such as semiconductors. The investigation of the femtosecond dynamics on nanometer length scales provides insight into the mechanisms that determine their structure, charge-, and energy-transfer. That understanding on the nano- and intermolecular scale will ultimately allow for the systematic design of functional materials such as membranes, polymers, or organic photovoltaic systems as well as control of their performance. This highly interdisciplinary research program also provides a broad learning environment for graduate and undergraduate students. As part of this effort, the Prof. Raschke is making the chemical nano-spectroscopy techniques developed broadly available through industry collaborations and at user facilities at National Labs.