Faculty Assistant

TeShima Brennen
Frick Laboratory, 121

Research Focus

Gregory Scholes video interviewThe 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.

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.

Figure: Left side shows micrographs of various photosynthetic cryptophyte algae. Their different colors arise from different chromophores in their light harvesting complexes. On the right side two crystal structures are shown of these light harvesting complexes. The remarkable change in structure from the ‘closed’ form (top) to the ‘open’ form (bottom) is controlled genetically and profoundly changes the function of the protein by changing the electronic coupling between the chromophores. 

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) Jessica M. Anna, Gregory D. Scholes, and Rienk van Grondelle “A Little Coherence in Photosynthetic Light Harvesting." Bioscience, 2014, 64, 14–25.

(3) Francesca Fassioli, Rayomond Dinshaw, Paul C. Arpin, and Gregory D. Scholes “Photosynthetic light harvesting: Excitons and coherence.” Royal Society: Interface, 2014, 11, 20130901.

(4) Gregory D. Scholes and Edward H. Sargent “Boosting Plant Biology.” Nature Mater., 2014, 13, 329–331.

(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.

Along with the development of quantum mechanics over the past century, scientists have been asking whether biology relies upon, or attains, functions by using quantum physics. This has progressed to the emergence of a field termed "quantum biology." Coherent light harvesting in photosynthesis is a prime example of quantum effects in biology.

In light of all that remains to be described regarding the study of life, the idea of quantum biology brings about a most important question: what do we really know about the fundamental nature and properties of the biological environment?

The concept of “warm, wet & noisy” is put forth when one imagines the complex components and workings of a biological system to be simply a messy business, incapable of supporting ‘delicate’ quantum processes. Whether it is an acceptance of quantum behavior, or generating a foundation for the study of difficult questions in biology, should we reconsider the premise that living entities are founded on uncorrelated and chaotic machinery? In other words, do we expect incoherence in biology? In our research we are pursuing fundamental issues connected with these kinds of questions.

Read more:

(6) Chanelle C. Jumper and Gregory D. Scholes “Life—Warm, wet and noisy? Comment on “Consciousness in the Universe: A Review of the ‘Orch OR’ Theory” by Hameroff and Penrose.”  J. Physics of Life Reviews, 2014, 11, 85–86.

Nanoscale systems are forecast to be a means of integrating desirable attributes of molecular and bulk regimes into easily processed materials. Notable examples include plastic light-emitting devices and organic solar cells, the operation of which hinge on the formation of spatially large and often complex electronic excited states, excitons, in nanostructured materials. The spectroscopy of nanoscale materials reveals details of their collective excited states, characterized by atoms or molecules working together to capture and redistribute excitation. What is special about excitons in nanometre-sized materials? We are interested in all kinds of excitons and we study a diverse range of materials to see how electronic excited states are formed and evolve on femtosecond time scales.

Read more:

Gregory D. Scholes & Garry Rumbles, “Excitons in Nanoscale Systems.” Nature Materials, 2006, 5, 683–696.

Obadiah Reid, Ryan Pensack, Yin Song, Gregory D. Scholes & Garry Rumbles “Charge Photogeneration in Neat Conjugated Polymers.” Chem. Mater., 2014, 26, 561–575.

Elisabetta Collini & Gregory D. Scholes, “Coherent intrachain energy migration in a conjugated polymer at room temperature.” Science, 2009323, 369-373.

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, 2009, 106, 3011–3016.

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

Research Areas
Spectroscopy / Physical Chemistry

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 (Tel Aviv University) (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

Reid, O. G.; Pensack, R. D.; Song, Y.; Scholes, G. D.; Rumbles, G., "Charge Photogeneration in Neat Conjugated Polymers." Chemistry of Materials 2014, 26 (1), 561-575.

Anna, J. M.; Scholes, G. D.; van Grondelle, R., "A Little Coherence in Photosynthetic Light Harvesting." Bioscience 2014, 64 (1), 14-25.

Harrop, S. J.; Wilk, K. E.; Dinshaw, R.; Collini, E.; Mirkovic, T.; Teng, C. Y.; Oblinsky, D. G.; Green, B. R.; Hoef-Emden, K.; Hiller, R. G.; Scholes, G. D.; Curmi, P. M. G., "Single-residue insertion switches the quaternary structure and exciton states of cryptophyte light-harvesting proteins." Proceedings of the National Academy of Sciences of the United States of America 2014, 111 (26), E2666-E2675.

McClure, S. D.; Turner, D. B.; Arpin, P. C.; Mirkovic, T.; Scholes, G. D., "Coherent Oscillations in the PC577 Cryptophyte Antenna Occur in the Excited Electronic State." Journal of Physical Chemistry B 2014, 118 (5), 1296-1308.

Hassan, Y.; Chuang, C.-H.; Kobayashi, Y.; Coombs, N.; Gorantla, S.; Botton, G. A.; Winnik, M. A.; Burda, C.; Scholes, G. D., "Synthesis and Optical Properties of Linker-Free TiO2/CdSe Nanorods." Journal of Physical Chemistry C 2014, 118 (6), 3347-3358.

Pensack, R. D.; Song, Y.; McCormick, T. M.; Jahnke, A. A.; Hollinger, J.; Seferos, D. S.; Scholes, G. D., "Evidence for the Rapid Conversion of Primary Photoexcitations to Triplet States in Seleno- and Telluro- Analogues of Poly(3-hexylthiophene)." Journal of Physical Chemistry B 2014, 118 (9), 2589-2597.

Tilley, A. J.; Pensack, R. D.; Lee, T. S.; Djukic, B.; Scholes, G. D.; Seferos, D. S., "Ultrafast Triplet Formation in Thionated Perylene Diimides." Journal of Physical Chemistry C 2014, 118 (19), 9996-10004.

Kobayashi, Y.; Chuang, C.-H.; Burda, C.; Scholes, G. D., "Exploring Ultrafast Electronic Processes of Quasi-Type II Nanocrystals by Two-Dimensional Electronic Spectroscopy." Journal of Physical Chemistry C 2014, 118 (29), 16255-16263.

Scholes, G. D.; Smyth, C., "Perspective: Detecting and measuring exciton delocalization in photosynthetic light harvesting." Journal of Chemical Physics 2014, 140 (11).

Jumper, C. C.; Anna, J. M.; Stradomska, A.; Schins, J.; Myahkostupov, M.; Prusakova, V.; Oblinsky, D. G.; Castellano, F. N.; Knoester, J.; Scholes, G. D., "Intramolecular radiationless transitions dominate exciton relaxation dynamics." Chemical Physics Letters 2014, 599, 23-33.

Anna, J. M.; Ostroumov, E. E.; Maghlaoui, K.; Barber, J.; Scholes, G. D., "Two-Dimensional Electronic Spectroscopy Reveals Ultrafast Downhill Energy Transfer in Photosystem I Trimers of the Cyanobacterium Thermosynechococcus elongatus." Journal of Physical Chemistry Letters 2012, 3 (24), 3677-3684.

Turner, D. B.; Arpin, P. C.; McClure, S. D.; Ulness, D. J.; Scholes, G. D., "Coherent multidimensional optical spectra measured using incoherent light." Nature Communications 2013, 4.

Zhang, M.; Hu, Y.; Hassan, Y.; Zhou, H.; Moozeh, K.; Scholes, G. D.; Winnik, M. A., "Slow morphology evolution of block copolymer-quantum dot hybrid networks in solution." Soft Matter 2013, 9 (37), 8887-8896.

Hossein-Nejad, H.; Olaya-Castro, A.; Fassioli, F.; Scholes, G. D., "Dynamical crossovers in Markovian exciton transport." New Journal of Physics 2013, 15.

Chang, Y.-L.; Song, Y.; Wang, Z.; Helander, M. G.; Qiu, J.; Chai, L.; Liu, Z.; Scholes, G. D.; Lu, Z., "Highly Efficient Warm White Organic Light-Emitting Diodes by Triplet Exciton Conversion." Advanced Functional Materials 2013, 23 (6), 705-712.

Myahkostupov, M.; Prusakova, V.; Oblinsky, D. G.; Scholes, G. D.; Castellano, F. N., "Structural Refinement of Ladder-Type Perylenediimide Dimers: A Classical Tale of Conformational Dynamics." Journal of Organic Chemistry 2013, 78 (17), 8634-8644.

Anna, J. M.; Song, Y.; Dinshaw, R.; Scholes, G. D., "Two-dimensional electronic spectroscopy for mapping molecular photophysics." Pure and Applied Chemistry 2013, 85 (7), 1307-1319.

Curutchet, C.; Novoderezhkin, V. I.; Kongsted, J.; Munoz-Losa, A.; van Grondelle, R.; Scholes, G. D.; Mennucci, B., "Energy Flow in the Cryptophyte PE545 Antenna Is Directed by Bilin Pigment Conformation." Journal of Physical Chemistry B 2013, 117 (16), 4263-4273.

Hwang, I.; Selig, U.; Chen, S. S. Y.; Shaw, P. E.; Brixner, T.; Burn, P. L.; Scholes, G. D., "Photophysics of Delocalized Excitons in Carbazole Dendrimers." Journal of Physical Chemistry A 2013, 117 (29), 6270-6278.

Oh, M. H. J.; Chen, M.; Chuang, C.-H.; Wilson, G. J.; Burda, C.; Winnik, M. A.; Scholes, G. D., "Charge Transfer in CdSe Nanocrystal Complexes with an Electroactive Polymer." Journal of Physical Chemistry C 2013, 117 (37), 18870-18884.

Ostroumov, E. E.; Mulvaney, R. M.; Anna, J. M.; Cogdell, R. J.; Scholes, G. D., "Energy Transfer Pathways in Light-Harvesting Complexes of Purple Bacteria as Revealed by Global Kinetic Analysis of Two-Dimensional Transient Spectra." Journal of Physical Chemistry B 2013, 117 (38), 11349-11362.

Zimmermann, J.; Mulet, R.; Wellens, T.; Scholes, G. D.; Buchleitner, A., "Efficiency scaling of non-coherent upconversion in a one-dimensional model system." Journal of Chemical Physics 2013, 138 (13).

Fassioli, F.; Oblinsky, D. G.; Scholes, G. D., "Designs for molecular circuits that use electronic coherence." Faraday Discussions 2013, 163, 341-351.

Ostroumov, E. E.; Mulvaney, R. M.; Cogdell, R. J.; Scholes, G. D., "Broadband 2D Electronic Spectroscopy Reveals a Carotenoid Dark State in Purple Bacteria." Science 2013, 340 (6128), 52-56.

Kolli, A.; O'Reilly, E. J.; Scholes, G. D.; Olaya-Castro, A., "The fundamental role of quantized vibrations in coherent light harvesting by cryptophyte algae." Journal of Chemical Physics 2012, 137 (17).