Rostock 2019 – scientific programme

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A: Fachverband Atomphysik

A 4: Atomic systems in external fields

A 4.5: Talk

Monday, March 11, 2019, 11:45–12:00, S HS 3 Physik

Many-body Kinetics of Dynamic Nuclear Polarization by the Cross Effect — •Federica Raimondi, Alexander Karabanov, Daniel Wisniewski, Igor Lesanovsky, and Walter Kockenberger — School of Physics & Astronomy, University of Nottingham, UK

Dynamic Nuclear Polarization (DNP) provides significant signal enhancement compared to conventional thermal polarization techniques used in typical nuclear magnetic resonance applications. The Cross Effect (CE) DNP mechanim, involving triple spin-flips between two interacting electrons and a nucleus, is the most efficient at low temperature and microwave irradiation amplitude. In silico optimization of parameters affecting CE enhancement, such as radical concentration and design, requires simulation of large spin systems. However, solving the Liouville-von Neumann equation for such systems quickly becomes intractable. Here, we show that the non-equilibrium nuclear polarization build-up is effectively driven by incoherent Markovian dissipative processes. These can be modelled using a highly efficient classical Kinetic Monte Carlo algorithm, which can accurately simulate systems consisting of over 100 spins within a reasonable time frame. With our theoretical approach, we have for the first time been able to study many-body processes such as spin diffusion.

We have since started to develop a fast simulation algorithm for the experimentally more relevant case of Magic Angle Spinning CE-DNP.