Diamond formation from C60 crystals heated under high pressure

X-ray Diffraction (XRD) and Raman Microspectroscopy showed that diamond is detected when solid C60 crystals are heated above 1600°C, in the 9-15 GP range. These samples are here studied by High Resolution Transmission Electron Microscopy (HRTEM) in order to allow the structural characteristics of more or less organised co-existing carbon phases

Controlling all Degrees of Freedom of the Optical Coupling in Hybrid Quantum Photonics

Nanophotonic quantum devices can significantly boost light-matter interaction which is important for applications such as quantum networks. Reaching a high interaction strength between an optical transition of a spin system and a single mode of light is an essential step which demands precise control over all degrees of freedom of the optical coupling. While current devices have reached a high accuracy of emitter positioning, the placement process remains overall statistically, reducing the device fabrication yield. Furthermore, not all degrees of freedom of the optical coupling can be controlled limiting the device performance. Here, we develop a hybrid approach based on negatively-charged silicon-vacancy center in nanodiamonds coupled to a mode of a Si$_3$N$_4$-photonic crystal cavity, where all terms of the coupling strength can be controlled individually. We use the frequency of coherent Rabi-oscillations and line-broadening as a measure of the device performance. This allows for iterative optimization of the position and the rotation of the dipole with respect to individual, preselected modes of light. Therefore, our work marks an important step for optimization of hybrid quantum photonics and enables to align device simulations with real device performance.Comment: 20 pages, 7 figure

Solid state synthesis of carbon-encapsulated iron carbide nanoparticles and their interaction with living cells †

Superparamagnetic carbon-encapsulated iron carbide nanoparticles (NPs), Fe 7 C 3 @C, with unique properties, were produced from pure ferrocene by high pressure-high temperature synthesis. These NPs combine the merits of nanodiamonds and SPIONs but lack their shortcomings which limit their use for biomedical applications. Investigation of these NPs by X-ray diffraction, electron microscopy techniques, X-ray spectroscopic and magnetic measurement methods has demonstrated that this method of synthesis yields NPs with perfectly controllable physical properties. Using magnetic and subsequent fractional separation of magnetic NPs from residual carbon, the aqueous suspensions of Fe 7 C 3 @C NPs with an average particle size of $25 nm were prepared. The suspensions were used for in vitro studies of the interaction of Fe 7 C 3 @C NPs with cultured mammalian cells. The dynamics of interaction of the living cells with Fe 7 C 3 @C was studied by optical microscopy using time-lapse video recording and also by transmission electron microscopy. Using novel highly sensitive cytotoxicity tests based on the cell proliferation assay and long-term live cell observations it was shown that the internalization of Fe 7 C 3 @C NPs has no cytotoxic effect on cultured cells and does not interfere with the process of their mitotic division, a fundamental property that ensures the existence of living organisms. The influence of NPs on the proliferative activity of cultured cells was not detected as well. These results indicate that the carbon capsules of Fe 7 C 3 @C NPs are air-tight which could offer great opportunities for future use of these superparamagnetic NPs in biology and medicine

Nitrogen and group-IV (Si, Ge) vacancy color centres in nano-diamonds: photoluminescence study at high temperature (25 °C–600 °C)

International audienc

Pressure-Temperature-Induced Transformations of Hydrocarbon- Fluorocarbon Mixtures into Nano- and Micron-Size Diamonds

International audienc