For our studies, we exploit synergetic effects resulting from combined experimental and theoretical approaches. In particular, we combine nuclear magnetic resonance and molecular dynamics simulations.

Methods

Dynamic range of methods

Condensed matter with disordered structure usually shows complex dynamics on various time and length scales. Therefore, a fundamental understanding requires a characterization of structure-dynamics relations over many orders of magnitude in time and length. For this endeavor, it is necessary to combine various methods. In the Vogel group, we use both experiments and simulations.

Our methods in detail

In experimental studies, we combine, in particular, nuclear magnetic resonance and broadband dielectric spectroscopy, complemented by calorimetric measurements and neutron scattering. In computational approaches, we perform molecular dynamics simulations for all-atom and coarse-grained models. Altogether, our combined methods explore molecular dynamics from the picoseconds to the seconds regimes and on length scales from about 0.1 nanometer to 100 micrometer.

Nuclear magnetic resonance (NMR)

We combine various NMR methods to investigate molecular dynamics in wide ranges of time and length scales.

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Molecular dynamics simulations

We develop coarse-grained models to reduce the number of pair interactions to be calculated and tackle the problem how to derive coarse-grained interaction potentials from the underlying all-atom force fields in a systematic manner.

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Technical developments

Development of NMR equipment

We continually develop home-built NMR equipment to open up new areas for applications. Central goals in this endeavor are the application of strong field gradients to achieve high spatial resolution or to measure slow molecular diffusion and the use of fast field cycling for broadband dynamical studies.

Strong field gradients for high spatial resolution

We employ magnetic field gradients to perform spatially resolved studies of structurally and dynamically inhomogeneous samples and develop versatile sample positioning systems. In this way, we achieve a very high 1D resolution of ca. 2 micrometer.

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Strong field gradients for diffusion measurements

Compared to their pulsed counterparts, static field gradients can be much stronger so that smaller diffusion coefficients are accessible. We exploit this capability of static field gradient (SFG) experiments to observe slow diffusion in viscous, soft, and solid materials.

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Fast field cycling for broadband studies of dynamics

In our lab, a home-built field-cycling setup is continually improved to enhance the accessible frequency range. With an in-house active shielding system, it is possible to perform NMR experiments at the currently worldwide lowest Larmor frequency of 3 Hz.

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