Fig. 7
a 2D-colour mapping of the PL signal intensity of DND spin-coated on a glass microscope coverslip together with b schematics of the experimental setup. c The PL intensity profile along the “aa” cross-section. d The photoluminescence intensity versus time for the selected DND aggregate marked with a circle in the upper side of the 2D map shown in panel a, in the presence or absence of an external magnetic field. Laser excitation at 532 nm wavelength. Square, 201 × 201 pixels. Integration time is 3 ms/pixel. Step—100 nm. The excitation radiation is focused on the upper surface of the glass coverslip with deposited DND. In zero field (B = 0), only small changes of intensity, due to the blinking of some of the NV− colour centres occur. When magnetic field is temporally applied a large decrease of the PL intensity occurs. Upper left panel a: the left scale for PL intensity corresponds to the 2D mapping of another DND aggregate shown in the left bottom corner of the large 2D map. Upper right panel b: schematics of the experimental setup explaining the displacement of the permanent magnet above the coverslip relative to the deposited DND