Felix Castellano

Advanced spectroscopies with the state-of-the-art light sources provide unprecedented opportunities for capturing correlated electronic/nuclear motions in real time and mapping out excited state trajectories on the potential energy landscape. In particular, it is important to understand the impact of coherent electron and nuclear motions in energy and electron transfer processes that lead to chemical reactions, and how to control these motions to steer the reaction in desirable directions. The proposed work aims at directly measuring vibronic coherence in molecular systems and their effects in energy transfer processes in supramolecular systems or aggregates based on Pt(II) dimer molecules.

The proposed work selects transition metal complexes (TMCs) and their hybrids with inorganic nanoparticles (TMC/NP) as platforms to study effects of ultrafast coherent electronic or atomic motions in photochemical reactions to transfer energy and charges or to break or form bonds in chemical reactions. The project aims at understanding how ultrafast electronic and nuclear coherent motions in TMC and TMC/NP materials lead to selected outcomes in photochemical reactions, and how these chemical reactions can be controlled using external stimuli that couple with phases of the electronic and atomic motions. A key component of this program will be the direct detection of coherent nuclear and electronic motions correlated to light energy capture and conversion in TMC and TMC/NP systems using the femtosecond (fs) X-ray pulses from the X-ray free electron laser, Linac Coherent Light Source (LCLS). Both ultrafast laser and X-ray measurements will be used to track excited-state electronic and nuclear structural dynamics, coherent excited-states dynamics, and transitions from coherent excited to product states. Ultrafast X-ray studies at LCLS will be augmented with measurements from picosecond synchrotron X-ray slicing light sources to prototype LCLS experiments and characterize reaction outcomes using coherence phase relevant triggering schemes in TMC and TMC/NP materials. Theory will be partnered with experiments to achieve a fundamental understanding of excited-state electronic and nuclear coherences underlying photochemical reaction dynamics, and to elucidate and model spectral and dynamic features observed in the laser and X-ray experiments. The team includes experimentalists and theorists with the expertise ranging from synthesis, ultrafast laser spectroscopy, to forefront theoretical calculations to model coherent control and ultrafast photochemical reaction trajectories as well as X-ray absorption/emission spectroscopy and scattering. The cohesive approach of this project is organized by two themes: 1.) ultrafast electronic and structural coherence in TMC and TMC/NP materials relevant to solar energy conversion and catalysis, 2.) coherent control of electron/energy transfer in transition metal complex/nanoparticle interfacial energy/electron transfer processes on the ultrafast time scales.

The mission of the Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE) is to evaluate molecule/materials hybrids for cooperative sunlight-driven generation of liquid fuels from CO2, H2O, and N2. The CHASE approach relies on fundamental mechanistic studies to develop and evaluate technological advances that harness the individual strengths of molecules and materials to cooperatively overcome longstanding challenges in the robust and selective conversion of abundant feed-stocks to liquid fuels and O2 driven by sunlight. This approach requires a diverse and deeply collaborative research Hub. Led by a core team at the University of North Carolina at Chapel Hill (UNC), CHASE features strategic satellite teams at proximal institutions. The team structure will provide scientific expertise and research infrastructure to: (a) synthesize new atomically and morphologically precise molecule/ materials hybrids for solar energy conversion, (b) address questions of unparalleled depth about structure, dynamics, and mechanism in complex hybrids, and (c) rapidly build on discoveries to expand basic energy science knowledge and prepare the next generation of solar fuels scientists. The fundamental challenges in liquid solar fuels generation are now clear, thanks in part to JCAP research. The CHASE approach, defined by precise molecule/materials hybrids and comprehensive mechanistic inquiry through sophisticated theory and advanced photophysical, photochemical, and catalysis studies, will provide ever-deeper understanding and design principles to overcome these challenges and make liquid solar fuels a reality.

We propose a quantum spin technology to image biochemical pathways in the rhizosphere with unprecedented chemical detail and sensitivity. Specifically, the proposed technology transfers the quantum entangled nuclear spin order of hydrogen gas, to metabolites, including nitrate, amino acids, nitrogen and pyruvate, to enable molecular imaging of their metabolic transformations without any penetration depth limitations such that molecular turnover and metabolism can be observed directly in soil.

Our mission is inspired by the way in which photosynthesis combines the energy of two or more photons to perform chemistry that is otherwise strongly uphill at equilibrium. We will employ light harvesting and advances in solar photochemistry to enable unprecedented photoinduced crosscoupling reactions that valorize abundant molecules. The energy input required to transform stable and abundant molecules to valuable products is greatly reduced by the use of catalysts. A fundamental aim in catalysis is to devise new ways to convert plentiful and unreactive molecules to valuable ones for energy-relevant applications. The research proposed for the BioLEC Energy Frontier Research Center (EFRC) will expand our fundamental understanding of both solar photochemistry and photosynthetic systems to enable sophisticated photoinduced cross-coupling chemistry. The resulting breakthroughs will lead to valuable chemicals, fuels, and materials. At the frontier of this endeavor, we aim to catalyze reactions that have prohibitive energy barriers for equilibrium chemistry������������������reactants are more stable than products. The reactions that we target are presently inconceivable using the leading edge of modern synthetic chemistry. Our approach is inspired by the way in which nature combinesthe energy of multiple photons to ramp up redox capability beyond that achievable with the energy from a single photon. To succeed, BioLEC brings together scientific communities that rarely interact������������������organic synthesis, structural and molecular biology, and physical chemistry.