The nitrogen-vacancy (NV) colour centre in diamond is an important physical system for emergent quantum technologies, including quantum metrology, information processing and communications, as well as for various nanotechnologies, such as biological and sub-diffraction limit imaging, and for tests of entanglement in quantum mechanics. Given this array of existing and potential applications and the almost 50 years of NV research, one would expect that the physics of the centre is well understood, however, the study of the NV centre has proved challenging, with many early assertions now believed false and many remaining issues yet to be resolved. This review represents the first time that the key empirical and ab initio results have been extracted from the extensive NV literature and assembled into one consistent picture of the current understanding of the centre. As a result, the key unresolved issues concerning the NV centre are identified and the possible avenues for their resolution are examined.

The nitrogen-vacancy colour centre in diamond

Fluorescent nanodiamond is a new nanomaterial that possesses several useful properties, including good biocompatibility1, excellent photostability1,2 and facile surface functionalizability2,3. Moreover, when excited by a laser, defect centres within the nanodiamond emit photons that are capable of penetrating tissue, making them well suited for biological imaging applications1,2,4. Here, we show that bright fluorescent nanodiamonds can be produced in large quantities by irradiating synthetic diamond nanocrystallites with helium ions. The fluorescence is sufficiently bright and stable to allow three-dimensional tracking of a single particle within the cell by means of either one- or two-photon-excited fluorescence microscopy. The excellent photophysical characteristics are maintained for particles as small as 25 nm, suggesting that fluorescent nanodiamond is an ideal probe for long-term tracking and imaging in vivo, with good temporal and spatial resolution.

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Mass production and dynamic imaging of fluorescent nanodiamonds.

Mass production and dynamic imaging of fluorescent nanodiamonds

Signaling by H2S is proposed to occur via persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH). Persulfidation provides a framework for understanding the physiological and pharmacological effects of H2S. Due to the inherent instability of persulfides, their chemistry is understudied. In this review, we discuss the biologically relevant chemistry of H2S and the enzymatic routes for its production and oxidation. We cover the chemical biology of persulfides and the chemical probes for detecting them. We conclude by discussing the roles ascribed to protein persulfidation in cell signaling pathways.

Chemical Biology of H2S Signaling through Persulfidation.

Nitric Oxide Binding Properties of Neuroglobin A CHARACTERIZATION BY EPR AND FLASH PHOTOLYSIS

Two thallium atom defects of tetragonal symmetry around $〈100〉$ are produced by x irradiation above 230 K in KCl: TlCl. Their electron-spin-resonance spectra are characterized by comparable and large $g$ shifts but quite different hyperfine parameters. A relativistic many-body calculation of the ${\mathrm{Tl}}^{0}$ atom hyperfine interaction including the effect of a tetragonal crystal field permits a quantitative analysis of the spin-Hamiltonian parameters. It is found in particular that the hyperfine data of the two ${\mathrm{Tl}}^{0}$ defects can be explained by assuming the presence of one or two perturbing positive charges, respectively, and a corresponding 35 and 45% delocalization of the $6{p}^{1}$ electron on the surrounding lattice. This analysis together with x-ray production, optical-excitation, and pulse-anneal data and the fact that both ${\mathrm{Tl}}^{0}$ defects can only be produced at temperatures where negative-ion vacancies are mobile (g230 K) allows one to propose precise defect structures: In one defect the ${\mathrm{Tl}}^{0}$ atom (on a positive-ion site) is associated with a single negative-ion vacancy in a nearest-neighbor position along $〈100〉$; in the other one, the ${\mathrm{Tl}}^{0}$ is flanked by two nearest-neighbor negative-ion vacancies along $〈100〉$. The data also provide strong evidence for the existence of a defect consisting of a ${\mathrm{Tl}}^{+}$ ion and a nearest-neighbor anion vacancy.

Electron-spin-resonance study of Tl atom defects in KCl and relativistic many-body analysis of the hyperfine structure

Spectroscopy of the ns1‐Centers in Ionic Crystals

http://www.ph.unito.it/dfs/solid/PUBBLICAZIONI/PUB2001-1.pdf

Sergiu V. Nistor

Papers

Nitric Oxide Binding Properties of Neuroglobin A CHARACTERIZATION BY EPR AND FLASH PHOTOLYSIS

Electron-spin-resonance study of Tl atom defects in KCl and relativistic many-body analysis of the hyperfine structure

Spectroscopy of the ns1‐Centers in Ionic Crystals

Ionoluminescence in CVD diamond and in cubic boron nitride

Synthesis and characterization of Mn2+ doped ZnS nanocrystals self-assembled in a tight mesoporous structure