New Publication: Photoluminescence from NV− Centres in 5 nm Detonation Nanodiamonds: Identification and High Sensitivity to Magnetic Field
Congratulations to fourth year PGR Ben Hogan, who has co-authored a paper on ‘Photoluminescence from NV− Centres in 5 nm Detonation Nanodiamonds: Identification and High Sensitivity to Magnetic Field’, published last week in Nanoscale Research Letters. The paper was the result of a collaboration with Ioffe Institute (St. Petersburg, Russia), Université Paris-Sud & Université Paris-Saclay (Paris, France), and Hosei University (Tokyo, Japan).
Ben explains the significance of this work:
This work looks at the properties of the tiny diamonds formed during the detonation of explosives. Particularly, we look at how light can be emitted from the diamonds due to the defects that occur within them as a result of their violent creation. The diamonds have applications in imaging, as the emission is both very bright and confined to a small area, amongst others. Such diamonds have, for example, previously been used to image inside cells as their small sizes mean they can easily move within biological samples. The key results from this paper are that the method used to produce the diamonds gives a high concentration of defects, and therefore brighter emission, and the demonstration that quantum effects allow us to switch the emission on or off by using a magnetic field.
Ben’s previous publications include ‘Transmission Properties of FeCl3-Intercalated Graphene and WS2 Thin Films for Terahertz Time-Domain Spectroscopy Applications’, co-authored with fellow fourth year PGR Kieran Walsh. His PhD project is on 2D liquid crystal composites for integrated optoelectronic devices, supervised by Dr. Anna Baldycheva & Dr. Monica Craciun.
The content of nitrogen-vacancy (NV−) colour centres in the nanodiamonds (DNDs) produced during the detonation of nitrogen-containing explosives was found to be 1.1 ± 0.3 ppm. This value is impressive for nanodiamonds of size < 10 nm with intentionally created NV− centres. The concentration was estimated from the electron paramagnetic resonance as determined from the integrated intensity of the g = 4.27 line. This line is related with “forbidden” ∆ms = 2 transitions between the Zeeman levels of a NV− centre’s ground triplet state. Confocal fluorescence microscopy enables detection of the red photoluminescence (PL) of the NV− colour centres in nanoscale DND aggregates formed from the 5-nm nanoparticles. Subwavelength emitters consisting of NV− with sizes a few times smaller than the diffraction-limited spot are clearly distinguished. We have further observed an abrupt drop in the PL intensity when mixing and anti-crossing of the ground and excited states spin levels in NV− occurs under an applied external magnetic field. This effect is a unique quantum feature of NV− centres, which cannot be observed for other visible domain light-emitting colour centres in a diamond lattice.