研究领域
Physical Chemistry/Chemical Physics
Ultrafast Nonlinear Optical Spectroscopy of Liquids
Dynamics of Complex Fluids
Physical Chemistry of Ionic Liquids
Supercooled Liquids and the Glass Transition
The research of Professor Quitevis is directed toward understanding liquid-state dynamics. The focus of our current research is on the dynamics of complex fluids, in particular, room temperature ionic liquids and supercooled liquids.
One of the main techniques used in my laboratory is optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). OHD-RIKES is an ultrafast nonlinear optical time-domain technique that measures the collective polarizability anisotropy dynamics of a liquid. By use of a Fourier-transform deconvolution procedure, the OHD-RIKES transient can be converted to a reduced spectral density or optical Kerr effect (OKE) spectrum, which is directly related to the depolarized Raman spectrum of the liquid and contains information about the low-frequency intermolecular modes of the liquid. To study the ultraslow dynamics in glass-forming liquids, fluorescence recovery after photobleaching (FRAP) techniques are used. In FRAP, the rotational and transitional motions of photobleachable fluorescent probe molecules are used. Since the technique monitors the recovery of the fluorescence of the probe after photobleaching, the timescale of the dynamics that we are measuring is not limited by the fluorescence lifetime of the probe. In translational diffusion measurements, the washing out of a spatially periodic pattern of bleached and unbleached probe molecules is followed, whereas in rotational diffusion measurements, the filling in of an orientational hole is followed.
Ionic Liquids: Room temperature ionic liquids (ILs) are commonly defined as salts with melting points below 373K. An IL is composed of a bulky organic cation and one of a range of common anions, which might be either organic or inorganic, and possesses negligible vapour pressure, low flammability, and a wide liquid range. The vast number of potential ILs (over a million simple ones and over a trillion ternary systems) means that ILs can be designed specifically with tuneable physicochemical properties, leading to their description as “designer” solvents. Because they offer unique sets of properties not achievable with other materials, there is increasing interest in applications beyond solvents in such wide ranging fields as energetic materials, biotechnology, and nanoscience. Despite the great success of this application-driven research, a fundamental understanding of the structure, dynamics, and interactions in these complex fluids is still lacking. A particularly important feature of ILs is that they are structured liquids characterized by nanoscopic polar and nonpolar domains. Understanding the relationship between this nanostructural organization and the intermolecular dynamics in ILs is one of the main themes guiding research in my group.
Supercooled Liquids: The dramatic viscous slow down that accompanies the formation of glasses upon cooling supercooled liquids to below the glass transition temperature Tg is one of the oldest and most extensively studied problems in condensed matter physics and chemistry. The microscopic causes of the viscous slow down responsible for the glass transition however remain an unsolved problem. We are currently studying translational and rotational diffusion in glass-forming liquids above and below Tg. The goal of this research is to further understand the decoupling between translational and rotational diffusion that occurs as Tg is approached from above in the supercooled state and the processes that underlie physical aging when the glass-former is quenched from a temperature above Tg to the glassy state. Current theories of the glass transition are based on the existence of dynamic heterogeneity near Tg. Experiments in my laboratory are aimed at revealing the relationship between decoupling, physical aging, and dynamic heterogeneity. FRAP techniques are being used to measure the ultraslow translational and rotational diffusion near Tg.
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"Heterogeneous Dynamics in Ionic Liquids at the Glass Transition: Fluorescence Recovery After Photobleaching Measurements of Probe Rotational Motion from Tg-10 K to Tg+4 K," F. Bardak, J. R. Rajian, P. Son, and E. L. Quitevis, J. Non-Cryst. Solids, 407, 2015, 324-332. Published on Web 10/8/2014. (Invited paper for 7th IDMRCS special issue.)
"Direct Exfoliation of Graphene in Ionic Liquids with Aromatic Groups," R. Bari, G. Tamas, Fahmida Irin, A. Aquino, M. J. Green, and E. L. Quitevis, Coll. Surf. A, 59, 2014, 63-69. Published on Web 09/20/2014.
"Thermophysical Properties of Imidazolium-Based Ionic Liquids: The Aliphatic versus Aromatic Functionality," R. Tao, G. Tamas, L. Xue, S. L. Simon, E. L. Quitevis, J. Chem. Eng. Data, 59, 2014, 2717-2724. Published on Web 07/30/2014
"Structure and Intermolecular Dynamics of Equimolar Benzene and 1,3-Dimethylimidazolium Bis[(trifluoromethane)sulfonyl]amide Mixture: Molecular Dynamics Simulations and OKE Spectroscopic Measurements," R. M. Lynden-Bell, L. Xue, G. Tamas, and E. L. Quitevis, J. Chem. Phys., 141, 044506 (2014). Published on Web 07/28/2014
"Probing the Interplay between Electrostatic and Dispersion Interactions in the Solvation of Nonpolar Nonaromatic Solutes in Ionic Liquids: OKE Spectroscopic Study of CS2/[CnC1im][NTf2] Mixtures (n = 1-4)," L. Xue, G. Tamas, E. Gurung, and E. L. Quitevis, J. Chem. Phys., 140, 164512 (2014). Published on Web 04/29/2014.
"OKE Spectroscopy and Molecular Dynamics Simulations of Polar and Nonpolar Molecules in Ionic Liquids," E. L. Quitevis, F. Bardak, D. Xiao, L. G. Hines, Jr., P. Son, R. A. Bartsch, P. Yang, and G. A. Voth, in Ionic Liquids: Science and Applications, A. E. Visser, N. J. Bridges, R. D. Rogers, Eds.; ACS Symposium Series 1117; American Chemical Society, Washington, DC, 2012; Chapter 13, pp 271-287.
"Nanostructural Organization in Acetonitrile/Ionic Liquid Mixtures: Molecular Dynamics Simulations and Optical Kerr Effect Spectroscopy," F. Bardak, D. Xiao, L. G. Hines Jr., P. Sun, R. A. Bartsch, E. L. Quitevis, P. Yang. and G. A. Voth, ChemPhysChem, 13, 1687-1700 (2012). Published on Web 04/23/12. (Featured on the cover of ionic liquids special issue.)
"Nanostructural Organization in Carbon Disulfide/Ionic Liquid Mixtures: Molecular Dynamics Simulations and Optical Kerr Effect Spectroscopy," P. Yang, G. A. Voth, D. Xiao, L. G. Hines, Jr., R. A. Bartsch, and E. L. Quitevis, J. Chem. Phys., 135, 034502 (2011). Published on Web 07/18/11.
"Effect of Cation Symmetry on the Morphology and Physicochemical Properties of Imidazolium Ionic Liquids," W. Zheng, A. Mohammed, L. G. Hines Jr., D. Xiao, O. J. Martinez, R. A. Bartsch, O. Russina, A. Triolo, and E. L.Quitevis, J. Phys. Chem. B, 115, 6572-6584 (2011). Published on Web 05/02/11.
"Effect of Cation Symmetry on the Low-Frequency Spectra of Imidazolium Ionic Liquids: OKE and Raman Spectroscopic Measurements and DFT Calculations," D. Xiao, L. G. Hines, Jr., M. W. Holtz, K. Song, R. A. Bartsch, E. L. Quitevis, Chem. Phys. Lett., 497, 37-52 (2010).
"Morphology and Intermolecular Dynamics of 1-Alkyl-3-methylimidazolium Bis[(trifluoromethane)sulfonyl]amide Ionic Liquids: Structural and Dynamic Evidence of Nanoscale Segregation", O. Russina, A. Triolo, L. Gontrani, R. Caminiti, D. Xiao, L. G. Hines, Jr., R. A. Bartsch, E. L. Quitevis, N. Pleckhova, K. R. Seddon, J. Phys.: Condens. Matter, 21, 424121 (2009). Published on Web 10/01/09. (Special issue on "Strong coulomb correlations in condensed matter: ionic liquids, electrolytes, and polyelectrolytes.")
"Effect of Cation Symmetry and Alkyl Chain Length on the Structure and Intermolecular Dynamics of 1,3-Dialkylimidazolium Bis(trifluoromethanesulfonyl)amide Ionic Liquids," D. Xiao, L. G. Hines, Jr., S. Li, R. A. Bartsch, E. L. Quitevis, O. Russina, A. Triolo, J. Phys. Chem. B, 113, 6426-6433 (2009). Published on Web 04/09/09. (Top 20 most cited paper in J. Phys. Chem. B. in 3 years after publication.)
"Intermolecular Vibrational Motions of Solute Molecules Confined in Nonpolar Domains of Ionic Liquids," D. Xiao, L. G. Hines, Jr., R. A. Bartsch, E. L. Quitevis, J. Phys. Chem. B, 113, 4544-4548 (2009) Published on Web 03/13/09.
"Nanostructural Organization and the Anion Effects in the Optical Kerr Effect Spectra of Binary Ionic Liquid Mixtures," D. Xiao, J. R. Rajian, L. G. Hines, Jr., S. Li, R. A. Bartsch, E. L. Quitevis, J. Phys. Chem. B, 112, 13316-13325 (2008). Published on Web 09/30/08.
"Translational Diffusion in Sucrose Benzoate Near the Glass Transition: Probe Size Dependence in the Breakdown of the Stokes-Einstein Equation," J. R. Rajian, E. L. Quitevis, J. Chem. Phys., 126, 224506 (2007).
"Nanostructural Organization and Anion Effect on the Temperature Dependence of the Optical Kerr Effect Spectra of Ionic Liquids," D. Xiao, J. R. Rajian, A. Cady, S. Li, R. A. Bartsch, E. L. Quitevis, J. Phys. Chem. B, 111, 4669-4677 (2007). Published on Web 01/18/07. (One of 6 papers featured on the cover of special issue "Physical Chemistry of Ionic Liquids.").
"Additivity in the Optical Kerr Effect Spectra of Binary Ionic Liquid Mixtures: Implications for Nanostructural Organization," D. Xiao, J. R. Rajian, S. Li, R. A. Bartsch, E. L. Quitevis, J. Phys. Chem. B, 110, 16174-16178 (2006).
"Enhanced Translational Diffusion of Rubrene in Sucrose Benzoate," J. R. Rajian, W. Huang, R. Richert, and E. L. Quitevis, J. Chem. Phys. 124, 014510 (2006).
"Intermolecular Spectrum of Liquid Biphenyl Studied by Optical Kerr Effect Spectroscopy," J. R. Rajian, B.-R. Hyun, E. L. Quitevis, J. Phys. Chem. A, 108, 10107-10115 (2004).
"Temperature-Dependence of the Low-Frequency Spectrum of 3-Pentyl-1-methylimidazolium Bis(trifluoromethanesulfonyl)imide Studied by Optical Kerr Effect Spectroscopy," J. R. Rajian, S. Li, R. A. Bartsch, E. L. Quitevis, Chem. Phys. Lett., 393, 372-377 (2004).