Instrumentation to perform mid-infrared Site-Basis spectroscopy for measuring electronic delocalization
Abstract
This proposal requests funds to purchase equipment to build a multi-dimensional spectrometer for measuring coherent electronic delocalization across molecules in polariton microcavities using mid-infrared Site-Basis spectroscopy. A revolution in ultrafast laser technology has been taking place over the last few years with high-repetition rate Ytterbium (Yt) lasers replacing Ti-Sapphire laser technology. Amplified Yt lasers now generate almost as much pulse energy as Ti-Sapphire lasers but with an output of 100-times as many pulses. As a result, experiments can be performed in a fraction of the time and-or signal-averaged for higher sensitivities, making possible new ultrafast spectroscopies. This proposal requests funding to build a two-color ultrafast 2D spectrometer that operates shot-to-shot at 100 kHz repetition rates. It will enable many new experiments, including the expansion into the mid-IR of a recently funded AFOSR proposal on polariton microcavities made from semiconducting carbon nanotubes. Polaritons are receiving widespread attention because the coupling shifts the energy levels, leading to new phenomena such as enhanced energy and charge transport. To understand the physics one needs to know the extent of delocalization. But that is difficult, because many of the new energy levels are optically dark states and so cannot be probed with visible light. Using this new laser-spectrometer system, we will use the vibrational modes of molecules to determine the contribution of each type of molecule to the polariton wavefunction. Mid-IR Site-Basis spectroscopy will be a general technique, applicable to a wide range of systems, because vibrational modes are very well-separated from their electronic states, have frequencies that depend on structure, and frequency shifts caused by electronic excitation. This work expands the directions of our newly funded AFOSR grant and builds upon our world-renowned expertise in mid-IR spectroscopy and pulse shaping technology. We were the first research group to build a visible 2D spectrometer utilizing Yb laser technology and the third to build a mid-IR 2D spectrometer with commercial Yb lasers, each of which was enabled by the pulse shaping technology developed in our research group. The proposed two-color 2D system will be unique in the world, bring much needed insights into the wavefunctions of polariton microcavities, and make possible a wide-range of new experiments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 05, 2025
- Source ID
- FA95502410020
Entities
People
- Martin T. Zanni
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Wisconsin System