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MA: Fachverband Magnetismus

MA 57: Posters Magnetism II

MA 57.53: Poster

Donnerstag, 19. März 2020, 15:00–18:00, P3

Sensitivity improvements of EPR-on-a-Chip with rapid scan — •Silvio Künstner¹, Anh Chu², Boris Naydenov¹, Alexander Schnegg³, and Klaus Lips¹ — ¹Berlin Joint EPR Lab, Helmholtz-Zentrum Berlin — ²Institute of Smart Sensors, Universität Stuttgart — ³EPR4Energy, Max-Planck-Institut für Chemische Energiekonversion, Mülheim a.d. Ruhr

Electron paramagnetic resonance (EPR) is the method of choice to investigate and quantify paramagnetic impurities in e.g. semiconductor devices, proteins, catalysts and molecular nanomagnets. The design of conventional EPR spectrometers, however, limits the versatility for operando measurements. Here, we present an improved design of a miniaturised EPR spectrometer, implemented on a single microchip (EPRoC). On the chip, an array of coils, each from a voltage-controlled oscillator (VCO), with a diameter of a few 100 µm is used as both, mw source and detector. Due to its compactness, EPRoC can be incorporated in growth reactors, (electro)chemical cells or in UHV environments. However, EPRoC suffers from rather poor concentration sensitivity. The usage of a VCO allows frequency sweeps with scan rates up to 2,000 THz/s rendering EPRoC perfect for rapid frequency scan EPR. Rapid scan EPR can lead to a signal-to-noise improvement especially for samples with long relaxation times, which would otherwise be saturated in continuous wave EPR. In this contribution, we demonstrate the increased sensitivity of rsEPRoC, by investigating standard EPR samples and discuss applications that will benefit from the increased sensitivity.