Oxidizing Hexagonal Boron Nitride into Fluorescent Structures byPhotodissociated Directional Oxygen Radical

Modifying the wide band gap semiconductorhexagonal boron nitride (hBN) can bring new chances inphotonics. By virtue of the solvothermal/hydrothermal oxidationor functionalization, hBN can be converted intofluorescentnanodots. Until now, it has been a big challenge to drily oxidizehBN and turn it into brightfluorescent structures due to itssuperior chemical stability. Here, we report the oxidation ofmultilayer hBN intofluorescent structures by ultraviolet (UV,lambda=172 nm) photodissociated directional oxygen radical [O(3P)] in agradient magneticfield. The paramagnetic O(3P), produced in alow-pressure O2atmosphere, drifts toward hBN and then convertsit into boron nitride oxide (BNO) micro/nanometer structuresconstituted by BO, BO2, and O-doped hBN. For a properlyoxidized BNO substance, bright and photostable wide-band photoluminescence is realized with nanosecond-scaled lifetimes underthe excitation of UV and visible lights.