Rheological and rheodielectric hole burning spectroscopy for the investigation of supramolecular relaxation processes in small-molecule glass formers

• Applicant: Professor Dr. Roland Böhmer
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation ; Experimental Condensed Matter Physics
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319140174

To gain detailed insights into the complex interplay of motional processes in ring- and chain-forming hydrogen-bonded associates, the present project aims at destabilizing the supramolecular structure of suitable viscous liquids by subjecting them to large external shear fields. Also including Fourier methods, this calls for an adaptation and refinement of experimental protocols that are well established in the framework of nonresonant dielectric hole burning spectroscopy and transferrable to the field of nonlinear rheology. The quantitative description of measurements achievable using the mechanical techniques will require to adjust theoretical approaches that are known to allow for a faithful modeling of corresponding dielectric experiments. The major goal of these activities is to unravel the supramolecular mechanisms active in Debye-type liquids such as monohydroxy alcohols, secondary amides, and aqueous solutions. In particular, this involves the exploration of the so far largely uncharted mutual coupling of electrical and mechanical degrees of freedom in these fluids by means of combination experiments like rheodielectric spectroscopy and infrared absorption in frequency dependent shear fields.

• DFG Programme: Research Grants