Research and Teaching Interest
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| Amplitude map of the S0- T1(0-0) emission intensity for quinoxaline in viscous MTHF as a function of wavenumber and time. |
The experimental research in this group addresses the physical chemistry of soft condensed matter by optical spectroscopy and by dielectric relaxation experiments. We are interested in understanding the relaxation and transport phenomena in disordered materials and how they relate to the structure, dynamics, and interactions. Our research topics cover the phenomena associated with glass transitions, interfacial effects, geometric confinement, relaxation and retardation processes, details of the molecular dynamics, spatial heterogeneities, and the relation between macroscopic and microscopic properties.
The laboratory offers a variety of highly sensitive equipment for dielectric retardation and relaxation measurements. The orientational motion of molecules as well as the translational motion of ions can be recorded in a fully automated fashion over a wide range of frequencies, 20 nHz to 10 MHz, and temperatures, 25 K to 475 K. Typical samples are organic supercooled liquids, polymeric materials, solid state ionic conductors, and other glass-forming systems.
The optical laboratory is designed to measure phosphorescence solvation dynamics in a time window from 10 μs to 1 s and for temperatures in the range 25 K to 325 K by recording S0 - T1 (0-0) emission spectra and depolarization as a function of time. This technique of solvation dynamics probes dielectric and/or mechanical relaxation phenomena on molecular spatial scales (2-3 molecular diameters resolution). We also measure the rotational behavior of the probe molecules by time resolved
optical anisotropy. Typical samples are organic supercooled liquids and glasses as well as polymeric materials, as bulk sample or spatially confined to nanoporous media. |
Representative Publications
"Dynamics of Glass-Forming Liquids. XI. Fluctuating Environments by Dielectric Spectroscopy," W. Huang, R. Richert, J. Chem. Phys. 124, 164510.1 - 164510.7 (2006).
"Debye Type Dielectric Relaxation and the Glass Transition of Alcohols.," L.-M. Wang and R. Richert, J. Phys. Chem. B 109, 11091 - 11094 (2005).
"Heterogeneous Thermal Excitation and Relaxation in Supercooled Liquids," S. Weinstein, R. Richert, J. Chem. Phys. 123, 224506.1 - 224506.9 (2005).
"Intramicellar Glass Transition and Liquid Dynamics in Soft Confinement," L-M. Wang, F. He and R. Richert, Phys. Rev. Lett. 92, 095701.1 - 095701.4 (2004).
"Surface Induced Glass Transition in a Confined Molecular Liquid.," R. Richert and M. Yang, J. Phys. Chem. B 107, 895 - 898 (2003).
"Heterogeneous Dynamics in Liquids: Fluctuations in Space and Time.," R. Richert, J. Phys.: Condens. Matter 14, R703 - R738 (2002).
"Triplet State Solvation Dynamics: Basics and Applications.," R. Richert, J. Chem. Phys. 113, 8404 - 8429 (2000).
"Dynamics of Glass-Forming Liquids. II. Detailed Comparison of Dielectric Relaxation, DC-Conductivity and Viscosity Data.," F. Stickel, E.W. Fischer and R. Richert, J. Chem. Phys. 104, 2043-2055 (1996).
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