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"Photo-switchable radicals as reporter spins for quantum sensing with NV centers"
Abstract: Nuclear Magnetic Resonance (NMR) spectroscopy provides atomic-scale structural insights but requires large sample quantities due to sensitivity limits. On the other hand, single-molecule microscopy offers higher sensitivity but lacks the resolution to capture atomic interactions. This project aims to bridge these limitations by combining nanoscale magnetic sensing with nitrogen vacancy (NV) centers in diamond and single-molecule microscopy techniques. NV center based magnetic sensing is limited in its sensitivity and resolution by the distance between the sensor and the target. To overcome this, we introduce electronic spins on the diamond surface, serving as ‘reporters’ between the NV center and target molecules. We used stable radicals formed by the photoreduction of rhodamine-derived fluorescent dye molecules as reporter spins, with lifetimes exceeding an hour. Double Electron-Electron Resonance (DEER) measurements confirm the detection and coherent manipulation of these spins. This approach would enable the sensing of protons within dye molecules and extends to the study of dye-labeled samples. Our ongoing work focuses on integrating these super-resolution dyes for correlative fluorescence and magnetic imaging. This dye radical assisted quantum sensing would enable combining NV based NMR with single-molecule microscopy, facilitating the study of complex structures with higher sensitivity.
Bio: Lakshmy is a 5th year physics graduate student working for Mikael Backlund researching nanoscale magnetic sensing using quantum defects in diamond.