Contact
Faculty Assistant

Maura E. Matvey     
mmatvey@princeton.edu
Frick Laboratory, 121
609-258-3651

Research Focus

Gregory Scholes video interview

The Scholes Group studies how complex molecular systems in chemistry and biology interact with light. We are interested to learn the mechanisms for photo-initiated processes like solar energy conversion. In our research we use ultrafast lasers to time processes and reveal unforeseen details using multidimensional electronic spectroscopy. Analysis and deeper understanding of our experiments is helped by quantum chemical calculations and other theoretical work.

A key consequence of impulsive broad-band laser excitation is that the ensemble of chromophores is synchronized. What this means is that we can probe properties intrinsic to the chromophores, which would otherwise be obscured by ensemble averaging. We perform such experiments using various coherence spectroscopies enabled by ultrafast laser science. In particular, we produce and analyze “wavepackets”.

In recent work, the Scholes group has used coherence spectroscopies delved deeper into the origin and nature of coherence phenomena in photosynthesis, electron transfer, transition metal complexes, and excitonic systems. We have also used coherence to learn about the mechanisms underpinning condensed phase dynamics in systems ranging from semiconductors to electron transfer reactions. Scholes led a recent Department of Energy workshop to discuss the future of the coherence field, which resulted in a viewpoint paper published in Naturein 2017. Current initiatives include discovering how the wave basis of quantum theory can be evidenced in a chemical reaction and how vibrations in complex systems—like DNA strands—can be entrained in lock-step, thereby reduced the effects of decoherence and enabling DNA to act as a hole-transfer “wire”. Challenges include: Where do we look for these quantum effects, which are typically hidden or rapidly lost? What experiments might reveal them? A breakthrough in this area will enable ways of encoding, manipulating, and using quantum information in chemical systems. The Scholes group’s recent work on electron transfer reactions has elucidated how dispersion of vibrational wavepackets provides insights into microscopic dynamics on approach to the transition state.

Figure:(a) A contour map of broadband pump–probe data for cresyl violet solution, showing the oscillatory modulation on top of ground- and excited-state population dynamics. (b) Fourier-filtered pump–probe data revealing coherent oscillations of the strong Franck–Condon active modes. (c) Oscillations resolved from betaine-30 in acetonitrile by filtering various frequency ranges and back-Fourier transforming to the time domain in order to resolve the dephasing dynamics. 

Broad-band femtosecond spectroscopy choreographs ensembles. Time-dependent quantum mechanics provides a holistic description of a molecule’s structure and dynamics over all degrees of freedom, and can generally be related back to our familiar time-independent view by a simple Fourier transform. In the same way, time-resolved coherent spectroscopy is a comprehensive method for spectroscopy and dynamics. It provides time-domain information in the form of photo-initiated dynamics with a resolution down to femtoseconds, while simultaneously revealing a molecule’s frequency-domain spectroscopic content at a level of detail rarely realized by steady-state methodologies. The latter feature comes in the form of coherences, or wavepackets, whose time evolution maps out the complex multidimensional potential energy surfaces of the molecule.

Read more:

(1) Gregory D. Scholes, Graham R. Fleming, Lin X. Chen, Alán Aspuru-Guzik, Andreas Buchleitner, David F. Coker, Gregory S. Engel, Rienk van Grondelle, Akihito Ishizaki, David M. Jonas, Jeff S. Lundeen, James K.  McCusker, Shaul Mukamel, Jennifer P. Ogilvie, Alexandra Olaya-Castro, Mark A. Ratner, Frank C. Spano, K. Birgitta Whaley, Xiaoyang Zhu  “Utilizing Coherence to Enhance Function in Chemical and Biophysical Systems” Nature2017543, 647–656.

(2) Shahnawaz Rafiq and Gregory D. Scholes, “From Fundamental Theories to Quantum Coherences in Electron Transfer” J. Am. Chem. Soc.2018, in press.

(3) Shahnawaz Rafiq, Maté J. Bezdek, Paul J. Chirik, and Gregory D. Scholes, “Dinitrogen Coupling to a Terpyridine-Molybdenum Chromophore Switched on by Fermi-Resonance” Chem2019, in press.

(4) Chanelle C. Jumper, Paul Arpin, Scott McClure, Shahnawaz Rafiq, Jacob C. Dean, Jeffrey Cina, Phillip Kovac, Tihana Mirkovic & Gregory D. Scholes  “Broadband Pump-Probe Spectroscopy Quantifies Ultrafast Solvation Dynamics of Proteins and Molecules” J. Phys. Chem. Lett20167, 4722–4731.

(5) Madeline H. Elkins, Ryan Pensack, Andrew H. Proppe, Oleksandr Voznyy, Li Na Quan, Shana O. Kelley, Edward H. Sargent, and Gregory D. Scholes, “Biexciton Resonances Reveal Exciton Localization in Stacked Perovskite Quantum Wells” J. Phys. Chem. Lett20178, 3895–3901.

(6) Elliot J. Taffet, Yoann Olivier, Frankie Lam, David Beljonne and Gregory D. Scholes “Carbene–Metal–Amide Bond Deformation, Rather Than Ligand Rotation, Drives Delayed Fluorescence” J. Phys. Chem. Lett20189, 1620–1626 (2018).

Photosynthetic solar energy conversion, as one example of our research, occurs on an immense scale across the earth. It provides all of Earth’s oxygen and plays a deciding factor in global trends in climate, etc. Energy from sunlight is absorbed by special molecules, like chlorophyll, that are embedded in proteins, comprising the photosynthetic unit. Hundreds of these "chromophores" (light absorbing molecules) are used to harvest sunlight and direct the excitation energy to nature’s solar cells—proteins called reaction centers. Thus, these light-harvesting complexes compensate for the mismatch between solar irradiance and the optimal rate of reaction center operation.

Why study light harvesting? Through bio-inspiration we can learn how to design clever materials for energy capture, we discover new examples of photophysical processes, we more deeply understand light-initiated chemical dynamics. Incredible examples of light to energy conversion systems are found among the diverse photosynthetic organisms, ranging from tropical plants to crustose coralline red algae that dwell on the sea floor, 20 m under water covered with more than 1 m of ice cover. These examples are fascinating case studies, particularly in chemical physics, with experiments and theories revealing the mechanisms involved in the ultrafast energy transfer processes of light harvesting.

Read more:

(1) Gregory D. Scholes, Graham R. Fleming, Alexandra Olaya-Castro and Rienk van Grondelle, “Lessons from nature about solar light harvesting.”  Nature Chem., 2011, 3, 763–774.

(2) Margherita Maiuri, Maria B. Oviedo, Jacob C. Dean, Michael Bishop, Zi. S. D. Toa, Bryan M. Wong,Stephen McGill, Gregory D. Scholes “High Magnetic Field Detunes Vibronic Resonances in Photosynthetic Light Harvesting”.  J. Phys. Chem. Lett20189, 548–554.

(3) Chanelle C. Jumper, Shahnawaz Rafiq, Siwei Wang and Gregory D. Scholes, “From Coherent to Vibronic Light Harvesting in Photosynthesis”. Curr. Opinion in Chemical Biology2018,47, 39–46.

(4) Tihana Mirkovic, Evgeny E. Ostroumov, Jessica M. Anna, Rienk van Grondelle, Govindjee and Gregory D. Scholes “Light Absorption and Energy Transfer in the Antenna Complexes of Photosynthetic Organisms” Chem. Rev2017117, 249−293.

 (5) Elisabetta Collini, Cathy Y. Wong, Krystyna E. Wilk, Paul M. G. Curmi, Paul Brumer, and Gregory D. Scholes, “Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature.” Nature, 2010, 463, 644–648.

Research Areas
Spectroscopy / Physical Chemistry
Honors

ScotCHEM seminar series (2019)

Director of BioLEC, a DOE Energy Frontier Research Center (2018-2022)

Masuhara Lectureship Award, Asian Photochemical Conference (2016)

Beijing Institute of Technology Adjunct Professor, China (2016-2020)

Deputy Editor, Journal of Physical Chemistry Letters (2016-present)

Swiss Chemical Society Lectureship (2016)

Senior Fellow, CIFAR Biology, Energy, Technology Program (2015)

Professorial Fellow, School of Chemistry, The University of Melbourne (2015-2020)

Fellow, Royal Society of Chemistry (United Kingdom)

NSERC John C. Polanyi Award (2013)

Royal Society of Chemistry Bourke Award (2012)

Baden-Württemberg & Wissenschaftliche Gesellschaft Guest Professor, University of Freiburg (2012)

Visiting Professor, Beijing Institute of Technology (2011–2013)

The Raymond and Beverly Sackler Prize in Physical Sciences (2011)

Fellow, Royal Society of Canada (Academy of Science) (2009)

Royal Society of Canada Rutherford Memorial Medal in Chemistry (2007)

NSERC Steacie Memorial Fellow (2007–2009)

Chemical Institute of Canada Keith Laidler award (2006)

Alfred P. Sloan Foundation Fellow (2004–2006)

Selected Recent Publications

Shahnawaz Rafiq and Gregory D. Scholes, “From Fundamental Theories to Quantum Coherences in Electron Transfer” J. Am. Chem. Soc. Minor revision (2018). Perspective

Margherita Maiuri, Maria B. Oviedo, Jacob C. Dean, Michael Bishop, Zi. S. D. Toa, Bryan M. Wong, Stephen McGill, Gregory D. Scholes “High Magnetic Field Detunes Vibronic Resonances in Photosynthetic Light Harvesting” J. Phys. Chem. Lett.. 9, 548–554 (2018).

Chanelle C. Jumper, Shahnawaz Rafiq, Siwei Wang and Gregory D. Scholes, “From Coherent to Vibronic Light Harvesting in Photosynthesis” Curr. Opinion in Chemical Biology 47, 39–46 (2018).

Ryan D. Pensack, Andrew J. Tilley, Christopher Grieco, Evgeny E. Ostroumov, Geoffrey E. Purdum, Devin B. Granger, Daniel G. Oblinsky, Jacob C. Dean, John B. Asbury, Yueh-Lin Loo, Dwight S. Seferos, John E. Anthony, and Gregory D. Scholes, “Striking the right balance of intermolecular coupling for high-efficiency singlet fission” Chem. Sci. 9, 6240-6259 (2018).

Margherita Maiuri, Evgeny E. Ostroumov, Rafael G. Saer, Robert E. Blankenship, Gregory D. Scholes, “Coherent Wavepackets in the FMO Complex are Robust to Spectral Perturbations by Mutagenesis” Nature Chem. 10, 177–183 (2018).

Jacob, C. Dean & Gregory D. Scholes, “Coherence Spectroscopy in the Condensed Phase: Insights into Molecular Structure, Environment, and Interactions” Acc. Chem. Res. 50, 2746–2755 (2017).

Madeline H. Elkins, Ryan Pensack, Andrew H. Proppe, Oleksandr Voznyy, Li Na Quan, Shana O. Kelley, Edward H. Sargent, and Gregory D. Scholes, “Biexciton Resonances Reveal Exciton Localization in Stacked Perovskite Quantum Wells” J. Phys. Chem. Lett. 8, 3895–3901 (2017).

Gregory D. Scholes, Graham R. Fleming, Lin X. Chen, Alán Aspuru-Guzik, Andreas Buchleitner, David F. Coker, Gregory S. Engel, Rienk van Grondelle, Akihito Ishizaki, David M. Jonas, Jeff S. Lundeen, James K.  McCusker, Shaul Mukamel, Jennifer P. Ogilvie, Alexandra Olaya-Castro, Mark A. Ratner, Frank C. Spano, K. Birgitta Whaley, Xiaoyang Zhu  “Utilizing Coherence to Enhance Function in Chemical and Biophysical Systems” Nature 543, 647–656 (2017). DOI 10.1038/nature21425

Jacob C. Dean, Tihana Mirkovic, Zi S. D. Toa, Daniel Oblinsky & Gregory D. Scholes  “Vibronic Enhancement of Algae Light Harvesting” Chem (Cell Press) 1, 858–872 (2016).

Chanelle C. Jumper, Paul Arpin, Scott McClure, Shahnawaz Rafiq, Jacob C. Dean, Jeffrey Cina, Phillip Kovac, Tihana Mirkovic & Gregory D. Scholes  “Broadband Pump-Probe Spectroscopy Quantifies Ultrafast Solvation Dynamics of Proteins and Molecules” J. Phys. Chem. Lett. 7, 4722–4731 (2016).

Elsa Cassette, Ryan D. Pensack, Benoît Mahler and Gregory D. Scholes, “Room-Temperature Exciton Coherence and Dephasing in Two-dimensional Nanostructures” Nature Comm. 6, 6086 (2015).

Evgeny E. Ostroumov, Rachel M. Mulvaney, Richard J. Cogdell, Gregory D. Scholes “Broadband 2D Electronic Spectroscopy Reveals a Carotenoid Dark State in Purple Bacteria” Science 340, 52–56 (2013).

Gregory D. Scholes, Graham R. Fleming, Alexandra Olaya-Castro and Rienk van Grondelle, “Lessons from nature about solar light harvesting”  Nature Chem. 3, 763–774 (2011).

Elisabetta Collini, Cathy Y. Wong, Krystyna E. Wilk, Paul M. G. Curmi, Paul Brumer, and Gregory D. Scholes, “Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature”  Nature 463, 644–648 (2010).

Jeongho Kim, Vanessa M. Huxter, Carles Curutchet, Gregory D. Scholes, “Measurement of Electron-Electron Interactions and Correlations using Two-Dimensional Electronic Double-Quantum Coherence Spectroscopy” J. Phys. Chem. A 113, 12122–12133 (2009).

Marcus Jones, Shun S. Lo, & Gregory D. Scholes, “Quantitative modeling of the role of surface traps in CdSe/CdS/ZnS nanocrystal photoluminescence decay dynamics” Proc. Natl. Acad. Sci. USA 106, 3011–3016 (2009).

Elisabetta Collini & Gregory D. Scholes, “Coherent intrachain energy migration in a conjugated polymer at room temperature” Science 323, 369-373 (2009).

Vanessa M. Huxter, Anna Lee, Shun S. Lo, & Gregory D. Scholes, “CdSe nanoparticle elasticity and surface energy” Nano Letters 9, 405–409 (2009).

Cathy Y. Wong, Jeongho Kim, P. Sreekumari Nair, Michelle C. Nagy & Gregory D. Scholes, “Relaxation in the exciton fine structure of semiconductor nanocrystals” J. Phys. Chem. C 113, 795–811 (2009). Feature Article.

Gregory D. Scholes, Jeongho Kim, & Cathy Y. Wong, “Exciton spin relaxation in quantum dots measured using ultrafast transient polarization grating spectroscopy” Phys. Rev. B 73, 195325 (13 pages) (2006).