Kristen E. Brown

Northwestern University
2190 Campus Drive
Evanston, IL 60208-3113

E-mail:
kristen.brown[at]u.northwestern.edu

2010 - present
Ph.D. Student, Northwestern University (expected 2015)

Professional Preparation

2006 - 2010
B.S. Chemical and Biomolecular Engineering, Georgia Institute of Technology
Advisor: Professor Seth R. Marder

Research Description

The design of efficient artificial photosynthetic systems capable of mimicking electron transfer reactions in nature requires a fundamental understanding of light-harvesting, charge separation (CS), and charge transport. Although various covalent donor-acceptor systems have been developed to address each of these challenges in artificial photosynthesis, it is often unclear how nuclear motions within these complexes promote electron transfer.  In addition, as complex systems capable of self-ordering and self-assembling are developed for the conversion of photon energy to stored charges, understanding the contributions of nuclear motions to energy-wasting charge recombination (CR) processes becomes equally important. For example, these considerations play an important role in donor-bridge-acceptor systems being implemented in solar energy conversion technologies such as dye-sensitized solar cells. Time-resolved vibrational spectroscopy allows for the interrogation of structural changes that occur during these processes, which are difficult to resolve using transient absorption techniques. The recent development of femtosecond stimulated Raman spectroscopy (FSRS) overcomes several limitations of other vibrational spectroscopy techniques because it is insensitive to fluorescence or scattering, has high spectral (~10 cm-1) and temporal (~60 fs) resolution, and is self-phase matched. My project applies FSRS to studying ultrafast charge transfer in extended aromatic systems. Such systems include perylene, perylene monoimide, and perylene diimide in covalently bound architectures as well as in films. 

Publications

Direct Observation of Ultrafast Excimer Formation in Covalent Perylenediimide Dimers using Near-Infrared Transient Absorption Spectroscopy, K. E. Brown, W. A. Salamant, L. E. Shoer, R. M. Young, and M. R. Wasielewski, J. Phys. Chem. Lett. 5, 2588-2593 (2014). DOI: 10.1021/jz5011797. 14 Jul 2014

Triplet State Formation in Photoexcited Slip-Stacked Perylene-3,4:9,10-bis(dicarboximide) Dimers on a Xanthene Scaffold, K. M. Lefler, K. E. Brown, W. A. Salamant, S. M. Dyar, K. E. Knowles, and M. R. Wasielewski, J. Phys. Chem. A. 117, 10333-10345 (2013).

Exponential Distance Dependence of Photoinitiated Stepwise Electron Transfer in Donor–Bridge–Acceptor Molecules: Implications for Wirelike Behavior. Ricks, A. B.; Brown, K. E.; Wenninger, M.; Karlen, S. D.; Berlin, Y. A.; Co, D. T.; Wasielewski, M. R.: J. Am. Chem. Soc. 2012, 134, 4581-4588.

Fellowships and Awards

Northwestern University Presidential Fellowship, 2014 – 2016
Anna Louise Hoffman Award for Outstanding Graduate Research, 2015

L. Carroll King Graduate Student Teaching Award, 2010