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Benjamin J.
Department of Chemistry and Biochemistry, UCLA

Distinguished Professor

B.S. in Physics and Chemistry, University of Michigan; Ph.D., University of California at Berkeley (Advisor:  Charles B. Harris); NSF Postdoctoral Fellow in Chemistry, University of Texas at Austin (Advisor:  Peter J. Rossky); Postdoctoral Fellow, University of California at Santa Barbara (Advisor:  Alan J. Heeger).   Senior Editor, the Journal of Physical Chemistry Letters; UCLA Distinguished Teaching Award; Herbert Newby McCoy Award for Outstanding Research; Hanson-Dow Award for Excellence in Teaching; Camille Dreyfus Teacher-Scholar; Glenn T. Seaborg Award; Alfred P. Sloan Foundation Research Fellow; Research Corporation Cottrell Scholar Award; NSF CAREER Award in Chemistry; NSF Predoctoral Fellow; W. R. Grace and Co. Predoctoral Fellow.

Brief CV 


Our research is directed at building a molecular-level understanding of chemical reactivity in complex environments by studying the dynamics of condensed phase chemical reactions using both experimental and theoretical techniques: femtosecond lasers and molecular dynamics computer simulations. Our research efforts fall into two principle areas: studies of how solvent molecules control the choice of products or the rate of solution-phase chemical reactions, and investigations into the ultrafast photophysics and electronic structure of semiconducting polymers and their behavior when doped and when used in optoelectronic devices.  We also have worked in the past at fabricating three-dimensional microstructures using multiphoton lithography.

Our first main area of research centers around solvent effects on chemical reactivity. As a chemical reaction takes place in solution, chemical bonds are broken and formed and electrical charge is redistributed between reactants and products. The solvent environment responds (via molecular reorientation or translation) to these changes in charge distribution and in size and shape of the reacting species on a variety of time scales extending from femtoseconds to longer than microseconds. In our group, we use femtosecond pump-probe spectroscopies to experimentally monitor the course of solution phase chemical reactions in real time. With femtosecond time resolution, we are able to "watch" the motions of solvent molecules responding to chemical changes of reacting solutes, monitor the flow of energy between reacting species and the solvent, and identify the motion of electrons during charge transfer reactions. These experiments are accompanied by computer simulations, ranging from simple solutions of Newton's classical equations of motion to sophisticated algorithms allowing for quantum dynamics in the absence of the Born-Oppenheimer approximation. Our group develops new techniques for deriving the pseudopotentials needed in mixed quantum/classical simulations, solving the Schrödinger equation for electrons that reside largely between molecules, and calculating free energies of quantum mechanical objects in condensed phases.  Our simulations provide molecular detail that is unavailable from experiment; on the computer, for example, we can easily separate the roles of solvent rotational and translational motions in solvating a chemical species or in providing the energy needed to promote a charge transfer reaction.  Projects range from studies of model systems such as solvated electrons and diatomic molecules to investigations of large organic molecules with complex photochemistry.  Simulations are done in close connection to the femtosecond experiments, so that experimental results drive new simulations and vice-versa, providing students in the group with an opportunity to do both experimental and theoretical work. 

Our second main area of research is focused on the electronic structure and device physics of conjugated polymers. Conjugated polymers are remarkable materials that have the electrical properties of semiconductors but the mechanical properties and processing advantages of plastics. This gives these materials enormous commercial potential for use in light-emitting diodes, displays, thermoelectrics and photovoltaics that have large areas and are flexible. Upon photoexcitation, the electrons and holes created in semiconducting polymers interact with their environment, leading to relaxation processes on multiple time scales; many of the important dynamical issues are qualitatively similar to the solution-phase reactions discussed above.  For thermoelectrics, the polymers are doped with strong oxidizing or reducing agents; the redox potential of the dopant and the way its counterion interacts with the carriers on the polymer backbone are the main factors determining carrier mobility.  Thus, much of our work focuses on understanding the relationship between the structure and function of polymer-based active layers so that the morphology can be controlled and optimized for different applications.  We work to achieve this goal using information from femtosecond and steady-state spectroscopies,simulations and quantum chemistry calculations, and the device physics of working polymer thermoelectrics. Projects include: spectroscopic studies of the electronic structure of conjugated polymer films and doped films; manipulating the interactions between polymer chains and dopants using using sequential processing and/or self-assembly techniques; studying the physics of carriers in working polymer-based devices using a variety of techniques including the AC Hall effect; and studying the effects of different types of disorder both experimentally and theoretically. This work provides students the opportunity to learn fundamental photophysics, polymer processing techniques, and semiconductor device construction.


Ten Representative Recent Publications

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K. J. Mei, W. R. Borrelli, A. Vong and B. J. Schwartz, "Using Machine Learning to Understand the Causes of Quantum Decoherence in Solution-Phase Bond Breaking," J. Phys. Chem. Lett. 15, 903-11 (2024); DOI: 10.1021/acs.jpclett.3c03474. 

Y. Wu, Q. M. Duong, A. F. Simafranca, C. Z. Salamat, B. J. Schwartz and S. H. Tolbert, "Tuning the Crystal Structure of P3HT by Rub-Aligning Controls the Propensity for Chemical Doping," ACS Mater. Lett. 4, 489-97 (2024); DOI: 10.1021/acsmaterialslett.3c01543.

S. J. Park and B. J. Schwartz, "How Ions Break Local Symmetry:  Simulations of Polarized Transient Hole-Burning for Different Models of the Hydrated Electron in Contact Pairs with Na+," J. Phys. Chem. Lett. 14, 3014-22 (2023); DOI: 10.1021/acs.jpclett.3c00220.

E. C. Wu, C. Z. Salamat, O. Leon Ruiz, Z. Mehmedović, T. Qu, A. Kim, S. H. Tolbert and B. J. Schwartz, "Counterion Control and the Spectral Signatures of Polarons, Coupled Polarons and Bipolarons in Doped P3HT Films," Adv. Funct. Mater. 2213652 (2023); DOI: 10.1002/adfm.202213652.  

S. J. Park, W. A. Narvaez and B. J. Schwartz, "Ab Initio Studies of Hydrated Electron:Cation Contact Pairs:  Hydrated Electrons Simulated by Density Functional Theory are too Kosmotropic," J. Phys. Chem. Lett. 14, 559-66 (2023); DOI: 10.1021/acs.jpclett.2c03705.

W. A. Narvaez, E. C. Wu, S. J. Park, M. Gomez and B. J. Schwartz, "Trap-Seeking or Trap-Digging?  Photoinjection of Hydrated Electrons into Aqueous NaCl Solutions," J. Phys. Chem. Lett. 13, 8653-9 (2022); DOI: 10.1021/acs.jpclett.2c02243.

A. Vong, K. J. Mei, D. R. Widmer and B. J. Schwartz, "Solvent Control of Chemical Identity Can Change Photodissociation into Photoisomerization," J. Phys. Chem. Lett. 13, 7931-8 (2022); DOI: 10.1021/acs.jpclett.2c01955. 

D. A. Stanfield, Z. Mehmedović and B. J. Schwartz, "Vibrational Stark Effect Mapping of Polaron Delocalization in Chemically-Doped Conjugated Polymers," Chem. Mater. 33, 8489-500 (2021); DOI: 10.1021/acs.chemmater.1c02934. 

M. G. Voss, J. R. Challa, D. T. Scholes, P. Y. Yee, E. C. Wu, X. Liu, S. J. Park, O. Leon Ruiz, S. Subramaniyan, M. Chen, S. A. Jenekhe, X. Wang, S. H. Tolbert and B. J. Schwartz, "Driving Force and Optical Signatures of Bipolaron Formation in Chemically-Doped Conjugated Polymers," Adv. Mater. 2000228, 1-7 (2020); DOI: 10.1002/adma.202000228.

T. J. Aubry, J. C. Axtell, V. M. Basile, K. J. Winchell, J. R. Lindemuth, T. M. Porter, J-Y. Liu, A. N. Alexandrova, C. P. Kubiak, S. H. Tolbert, A. M. Spokoyny and B. J. Schwartz, "Dodecaborane-Based Dopants Designed to Shield Anion Electrostatics Lead to Increased Carrier Mobility in a Doped Conjugated Polymer," Adv. Mater. 1805647, 1-8 (2019);  DOI: 10.1002/adma.201805647.

Complete Publication List  (including links to full text of papers) last updated 1/20/24.

 If you have problems viewing any of these papers (all in PDF format), try "Save Target As" instead of viewing directly through your browser.  
Contact Info

Department of Chemistry & Biochemistry
Box 951569 (post)
607 Charles E. Young Drive East (courier)
Los Angeles, CA 90095-1569
Phone: (310) 206-4113
Fax: (310) 206-4038
Email: schwartz  at chem.ucla.edu

Student Office/Lab:  (310) 206-6418

Current members of the Schwartz Group

The Schwartz group in Jan 2024 

Front row, from left to right:  Xiaoyan Liu (postdoc), Kara Lo (grad student),
Ken Mei (grad student), Zerina Mehmedović (grad student), Cinnamon (group mascot),
Diego Garcia Vidales (grad student), Amanda Nguyen (undergrad student).

Back row, left to right:  Quynh Duong (grad student),  Hannah Liu (undergrad student),
Reid Wilson (grad student), Jose Guardado Sandoval (grad student), Ben Schwartz (PI),
Will Borrelli (grad student),  Alex Leon (grad student), Stephanie Jimenez (grad student),
Eric Wu (postdoc).

(for the Bitmoji version of the Schwartz group, click here).
(for the Southpark version of the Schwartz group, click here).

 Schwartz Group Photo Gallery

 Schwartz Group Press

 Evolution of the Schwartz Group
  Group Meeting Schedule

Please send comments on this page, notice of missing links, etc. to schwartz at chem.ucla.edu

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