研究领域

Physical Chemistry

The research in this group addresses the physical chemistry of glass-forming liquids and soft matter by dielectric relaxation experiments and by optical spectroscopy. We are interested in understanding the relaxation and transport phenomena in disordered materials and how they relate to the microscopic structure and dynamics. Our research topics cover phenomena associated with glass transitions, interfacial effects, geometric confinement, relaxation and retardation processes, non-linear responses, physical aging effects, 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, temperatures, 25 K to 475 K, and for fields up to 600 kV/cm. Typical samples are organic supercooled liquids, polymeric materials, hydrogen bonded liquids, biological and pharmaceutical materials, 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. Cartoon of spectral and concomitant spatial distribution in a supercooled liquid.

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Strain Induced Fragility Transition in Metallic Glass, H.-B. Yu, R. Richert, R. Maaß, K. Samwer, Nat. Commun. Probing Liquid Dynamics, One Molecule at a Time, R. Richert, Proc. Natl. Acad. Sci. U.S.A. Structural Recovery in Plastic Crystals by Time-resolved Non-linear Dielectric Spectroscopy, B. Riechers, K. Samwer, R. Richert, J. Chem. Phys. Thermal Stability of Vapor-Deposited Stable Glasses of an Organic Semiconductor, D. M. Walters, R. Richert, M. D. Ediger, J. Chem. Phys. On the Existence of and Mechanism for Microwave-Specific Reaction Rate Enhancement, G. B. Dudley, R. Richert, A. E. Stiegman, Chem. Sci. 6 (2015) 2144 - 2152 Quantum Effects in the Dynamics of Deeply Supercooled Water, A. L. Agapov, A. I. Kolesnikov, V. N. Novikov, R. Richert, A. P. Sokolov, Phys. Rev. E 91 (2015) 022312.1 - 022312.10 Dynamics of Glass-Forming Liquids. XVIII. Does Entropy Control Structural Relaxation Times? S. Samanta, R. Richert, J. Chem. Phys. 142 (2015) 044504.1 - 044504.10 Dopant Effects on 2-Ethyl-1-hexanol: A Dual-Channel Impedance Spectroscopy and Neutron Scattering Study, L. P. Singh, A. Raihane, C. Alba-Simionesco, R. Richert, J. Chem. Phys. 142 (2015) 014501.1 - 014501.8 Anomalously Large Isotope Effect in the Glass Transition of Water, C. Gainaru, A. L. Agapov, V. Fuentes-Landete, K. Amann-Winkel, H. Nelson, K. W. Köster, A. I. Kolesnikov, V. N. Novikov, R. Richert, R. Böhmer, T. Loerting, A. P. Sokolov, Proc. Natl. Acad. Sci. 111 (2014) 17402 - 17407 Non-linear Dielectric Behavior of a Secondary Relaxation: Glassy d-Sorbitol, S. Samanta, R. Richert, J. Phys. Chem. B (in press) Structure and Dynamics of Monohydroxy Alcohols - Milestones Towards their Microscopic Understanding, 100 Years After Debye, R. Böhmer, C. Gainaru, R. Richert, Physics Reports 545 (2014) 125 - 195 Role of Fragility in the Formation of Highly Stable Organic Glasses, A. Sepúlveda, M. Tylinski, A. Guiseppi-Elie, R. Richert, M. D. Ediger, Phys. Rev. Lett. 113 (2014) 045901.1 - 045901.5 Comment on "Third Order Susceptibilities in Supercooled Liquids and the 'Box Model' Theory versus Experiments" [J. Chem. Phys. 140, 054508 (2014)], S. Samanta, R. Richert, J. Chem. Phys. 140 (2014) 247101.1 - 247101.2 Dielectric Loss of Poly(vinylacetate) at Electric Fields of 400 kV/cm, U. Pathak, R. Richert, Colloid Polym. Sci. 292 (2014) 1905 - 1911 Fast Crystal Growth from Organic Glasses: Comparison of o-Terphenyl with Its Structural Analogs, C. T. Powell, K. Paeng, Z. Chen, R. Richert, L. Yu, M. D. Ediger, J. Phys. Chem. B 118 (2014) 8203 - 8209 Limitations of Heterogeneous Models of Liquid Dynamics: Very Slow Rate Exchange in the Excess Wing, S. Samanta, R. Richert, J. Chem. Phys. 140 (2014) 054503.1 - 054503.7 Frequency Dependence of Dielectric Saturation, R. Richert, Phys. Rev. E 88 (2013) 062313.1 - 062313.6 Dielectric Spectroscopy Study of Myoglobin in Glycerol-Water Mixtures, S. Roy, R. Richert, Biochim. Biophys. Acta 1844 (2014) 323 - 329 Dynamics of Glass-Forming Liquids. XVII. Dielectric Relaxation and Intermolecular Association in a Series of Isomeric Octyl Alcohols, L. P. Singh, C. Alba-Simionesco, R. Richert, J. Chem. Phys. 139 (2013) 144503.1 -144503.13 Comment on "Temperature Divergence of the Dynamics of a Poly(vinyl acetate) Glass: Dielectric vs. Mechanical Behaviors" [J. Chem. Phys. 136, 154901 (2012)], R. Richert, J. Chem. Phys. 139 (2013) 137101.1 - 137101.2 Supercooled Liquids and Glasses by Dielectric Relaxation Spectroscopy, R. Richert, Adv. Chem. Phys. 156 (2015) 101 - 195 Measurement of Conductivity and Permittivity on Samples Sealed in Nuclear Magnetic Resonance Tubes, W. Huang, C. A. Angell, J. L. Yarger, R. Richert, Rev. Sci. Instrum. 84 (2013) 073906.1 - 073906.5 On the Derivation of Equilibrium Relaxation Times from Aging Experiments, R. Richert, P. Lunkenheimer, S. Kastner, A. Loidl, J. Phys. Chem. B 117 (2013) 12689 - 12694 Dynamics of Glass-Forming Liquids. XVI. Observation of Ultrastable Glass Transformation via Dielectric Spectroscopy, Z. Chen, A. Sepúlveda, M. D. Ediger, R. Richert, J. Chem. Phys. 138 (2013) 12A519.1 - 12A519.8 Watching Hydrogen Bonded Structures in an Alcohol Convert from Rings to Chains, L. P. Singh, R. Richert, Phys. Rev. Lett. 109 (2012) 167802.1 - 167802.5 Experimental Studies of Debye-like Process and Structural Relaxation in Mixtures of 2-ethyl-1-hexanol and 2-ethyl-1-hexyl bromide, M. Preuß, C. Gainaru, T. Hecksher, S. Bauer, J. C. Dyre, R. Richert, R. Böhmer, J. Chem. Phys. 137 (2012) 144502.1 - 144502.10 Difficulties in Characterizing High-Resistivity Silicon, P. Nayak, R. Richert, D. K. Schroder, ECS Trans. 50 (2013) 259 - 268 On the Dynamics of Liquids in Their Viscous Regime Approaching the Glass Transition, Z. Chen, C. A. Angell, R. Richert, Eur. Phys. J. E 35 (2012) 65.1 - 65.7