Ground-State Depletion Nanoscopy of Nitrogen-Vacancy Centres in Nanodiamonds
J. Storteboom (Swinburne University of Technology, TU Delft - ImPhys/Microscopy Instrumentation & Techniques)
Martina Barbiero (The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust)
Stefania Castelletto (Swinburne University of Technology, Royal Melbourne Institute of Technology University)
Min Gu (Royal Melbourne Institute of Technology University, University of Shanghai for Science and Technology, Swinburne University of Technology)
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Abstract
The negatively charged nitrogen-vacancy (NV -) centre in nanodiamonds (NDs) has been recently studied for applications in cellular imaging due to its better photo-stability and biocompatibility if compared to other fluorophores. Super-resolution imaging achieving 20-nm resolution of NV - in NDs has been proved over the years using sub-diffraction limited imaging approaches such as single molecule stochastic localisation microscopy and stimulated emission depletion microscopy. Here we show the first demonstration of ground-state depletion (GSD) nanoscopy of these centres in NDs using three beams, a probe beam, a depletion beam and a reset beam. The depletion beam at 638 nm forces the NV - centres to the metastable dark state everywhere but in the local minimum, while a Gaussian beam at 594 nm probes the NV - centres and a 488-nm reset beam is used to repopulate the excited state. Super-resolution imaging of a single NV - centre with a full width at half maximum of 36 nm is demonstrated, and two adjacent NV - centres separated by 72 nm are resolved. GSD microscopy is here applied to NV - in NDs with a much lower optical power compared to bulk diamond. This work demonstrates the need to control the NDs nitrogen concentration to tailor their application in super-resolution imaging methods and paves the way for studies of NV - in NDs’ nanoscale interactions.