Department of Chemistry

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Sean Garrett-Roe

Assistant Professor

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216 EBERL
Chevron Science Center
219 Parkman Avenue

Pittsburgh, PA 15260
412-624-1283

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Research Overview

Ultrafast dynamics; nonlinear spectroscopy; biophysics; solvation dynamics; ion channels; ionic liquids.

The goal of the Garrett-Roe research group is to develop a deep understanding of structure and dynamics in the condensed phase, especially in complex systems. We have established a strong theme in the ultrafast dynamics of ionic liquids, and we are founding a parallel theme for the dynamics of ion-binding peptides.

[Text Box: Fig. 1) Ultrafast vibrational spectroscopy allows us to make “molecular movies” of ionic liquids to understand their physical chemistry and chemical physics to support their application as advanced electrolytes, carbon absorbents, and reaction media.]

Ionic liquids are salts that are molten at room temperature. They are liquids composed of cations and anions with no excess solvent. Ionic liquids are fascinating from both the practical and fundamental points of view. Their low vapor pressure, high thermal stability, and chemical tunability make them “green solvents” whose properties can be tuned for the application at hand. For example, these solvents show promise as reaction media, non-aqueous electrolytes, and carbon capture absorbents.

 

More than 1018 ionic liquids are possible, only the smallest fraction of which have been tested. What is missing is the fundmental understanding to guide the exploration of this large chemical space. The competition between intermolecular forces -- electrostatic attraction, dispersion, polarization, and hydrogen bonding -- makes the bulk properties of these fluids difficult to predict from their molecular properties. In the same way that solvation structure and dynamics dictate the behavior of simple liquids, so do they control the properties of this class of complex liquids.

 

To develop a deeper understanding of the molecular interactions in these complex solvents, we use ultrafast vibrational spectroscopy (2D-IR) to elucidate local structure and dynamics. Ultrafast spectroscopy has the time resolution to resolve intermolecular motions. Vibrational spectroscopy has the advantage of small, well-defined chromophores which can provide local chemical information. A comprehensive understanding of how molecular structure of the ionic liquid's components dictates the solvation dynamics will lead to the insights needed for the rational design and optimization of ionic liquids for many important properties, from their viscosity [1,2], to CO2 solubility [3,4], to catalytic properties [5].

Awards

  • 2006–08 National Science Foundation (USA) International Research Fellowship Program
  • 2008 Mettler Toledo-Prize, Swiss Chemical Society
  • 2007 ETH C4 Workshop prize
  • 1999 McKay Prize in Physical Chemistry, Princeton University

Year

2012

Publications

“Ultrafast structure and dynamics in ionic liquids: 2D-IR spectroscopy probes the molecular origin of viscosity,” Ren, Z., Ivanova, A. S., Couchot-Vore, D., and Garrett-Roe, S. , J. Phys. Chem. Lett. , Vol. 5, 2014, Pages 1541–1546
“Eutectic ionic liquid mixtures and their effect on CO2 solubility and conductivity,” . Ivanova, A. S., et al , RSC Adv., Vol. 5, 2015, Pages 51407–51412
“Two-dimensional ultrafast vibrational spectroscopy of azides in ionic liquids reveals solute-specific solvation,” Dutta, S., Ren, Z., Brinzer, T., and Garrett-Roe, S. , Phys. Chem. Chem. Phys., Pages Article ASAP (2015)
“(3D-IR) Spectroscopy of Isotopically Substituted Liquid Water Reveals Heterogeneous Dynamics,” Garrett-Roe S, Perakis F, Rao F, Hamm P, J. Phys. Chem. B, Article ASAP, 2011,
“Enhancing Signal Detection and Completely Eliminating Scattering Using Quasi-Phase-Cycling and (2D IR) Experiments,” Bloem R, Garrett-Roe S, Strzalka H, et al., Opt. Express, Vol. 18, 2010, Pages 27067
“Structural Inhomogeneity of Water by Complex Network Analysis,” Rao F, Garrett-Roe S, Hamm P, JOURNAL OF PHYSICAL CHEMISTRY B, Vol. 114, 2010, Pages 15598-15604
“The OH Stretch Vibration of Liquid Water Reveals Hydrogen-Bond Clusters,” Garrett-Roe S, Hamm P, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol. 12, 2010, Pages 11263-1126
“What Can We Learn From (3D-IR) Spectroscopy?,” Garrett-Roe S, Hamm P, ACCOUNTS OF CHEMICAL RESEARCH, Vol. 42, 2009, Pages 1412-1422
“Purely Absorptive Three-Dimensional Infrared Spectroscopy,” Garrett-Roe S, Hamm P, JOURNAL OF CHEMICAL PHYSICS, Vol. 130, 2009, Pages 164510
“On the Phasing Problem of Heterodyne-Detected Two-Dimensional Infrared Spectroscopy,” Backus EHG, Garrett-Roe S, Hamm P, OPTICS LETTERS, Vol. 33, 2008, Pages 2665-2667
“The Ultrafast Dynamics of Image Potential State Electrons at the Dimethylsulfoxide/Ag(111) Interface,” Strader ML, Garrett-Roe S, Szymanski P, et al., JOURNAL OF PHYSICAL CHEMISTRY C, Vol. 112, 2008, Pages 6880-6886
“Two-Photon Photoemission of Ultrathin Film PTCDA Morphologies on Ag(111),” Yang A, Shipman ST, Garrett-Roe S, et al., JOURNAL OF PHYSICAL CHEMISTRY C, Vol. 112, 2008, Pages 2506-2513
“2D-IR Spectroscopy of the Sulfhydryl Band of Cysteines in the Hydrophobic Core of Proteins,” Kozinski M, Garrett-Roe S, Hamm P, JOURNAL OF PHYSICAL CHEMISTRY B, Vol. 112, 2008, Pages 7645-7650