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Scientific highlights

Point Defects in h-BN as efficient UV quantum emitters

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Single photons sources (SPS) play a central role in the experimental foundation of quantum computing. Currently, there is a large scientific effort in identifying new bright and stable single-photon emission sources, with the aim of extending the spectral range achievable by quantum emitters. In the last years low dimensional layered semiconductors appeared as new promising optical materials and low energy SPS have been identified in transition metal dichalcogenides. In this work, thanks to a newly developed optical set-up integrated in a scanning transmission electron microscope, we have identified a new very bright UV single photon emitter in hexagonal boron nitride. Read more »

Revisiting Graphene Oxide Chemistry

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In the last decade, graphene oxide (GO) has attracted a widespread interest for its mechanical strength, tunable optoelectrical properties, simple processability and its potential as precursor for a low-cost and large-scale production of graphene (reduced graphene oxide, RGO). Nevertheless, after more than 150 year since its discovery, the type and distribution of oxygen functional groups in graphene oxide (GO) and reduced graphene oxide (RGO) remain still a subject of great debate. Currently, the most acknowledged model for GO corresponds to a random functionalization of the carbon basal plane with epoxide and hydroxyl groups, forming graphitic and partially oxidized domains. However, no definitive evidence of this model has been reported and local analytic techniques are required to access the chemistry of these materials at a nanometric scale. Electron energy loss spectroscopy in a scanning transmission electron microscope can provide the suitable resolution, but GO and RGO are extremely sensitive to electron irradiation. To solve this issue we employ an adapted experimental setup to reduce electron illumination below damage limit. Read more »

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