213 research outputs found
Boron Doped Diamond Electrodes for Direct Measurement in Biological Fluids: An In Situ Regeneration Approach
International audienceBoron doped diamond (BDD) electrodes are extremely promising in the field of biomedical applications as they exhibit a unique combination of properties. Despite these advantages, BDD electrodes are prone to fouling when used in biological fluids (urine, blood plasma), and synthetic fluids. We propose a electrochemical (EC) treatment where a train of short cathodic and/or anodic pulses are applied to clean fouled electrodes. This technique can be used to retrieve the lost reactivity, characterized by electron transfer rate k0 of the boron doped diamond electrodes, thereby enhancing their reusability over long period of measurements without degradation of the signal, thus significantly extending the field of monitoring and surveying applications. The technique does not require the use of a specific medium and thus can be directly performed in the probed fluid. Although an aqueous electrolyte containing non-electroactive species is preferred for EC activation, it can also be done in biological fluids such as blood, urine etc, thereby opening the field for analysis. Through Electrochemical impedance spectroscopy (EIS) it was observed that the k value was increased up to 0.1 cm s after the activation process. This technique improves the sensitivity, reproducibility and lifetime of the electrodes to a considerable extent
Strong Coupling of a Spin Ensemble to a Superconducting Resonator
We report the realization of a quantum circuit in which an ensemble of
electronic spins is coupled to a frequency tunable superconducting resonator.
The spins are Nitrogen-Vacancy centers in a diamond crystal. The achievement of
strong coupling is manifested by the appearance of a vacuum Rabi splitting in
the transmission spectrum of the resonator when its frequency is tuned through
the NV center electron spin resonance.Comment: 4 pages, 3 figure
In situ study of the initial stages of diamond deposition on 3C-SiC (100) surfaces: Towards the mechanisms of diamond nucleation
The mechanisms involved in the diamond nucleation on 3C-SiC surfaces have been investigated using a sequential in situ approach using electron spectroscopies (XPS, XAES and ELS). Moreover, diamond crystals have been studied by HRSEM. The in situ nucleation treatment allows a high diamond nucleation density close to 4 x 10(10) cm(-2). During the in situ enhanced nucleation treatment under Plasma, a negative bias was applied to the sample. The formation of an amorphous carbon phase and the roughening of the 3C-SiC surface have been observed. The part of these competing mechanisms in diamond nucleation is discussed
Surface-induced charge state conversion of nitrogen-vacancy defects in nanodiamonds
We present a study of the charge state conversion of single nitrogen-vacancy
(NV) defects hosted in nanodiamonds (NDs). We first show that the proportion of
negatively-charged NV defects, with respect to its neutral counterpart
NV, decreases with the size of the ND. We then propose a simple model
based on a layer of electron traps located at the ND surface which is in good
agreement with the recorded statistics. By using thermal oxidation to remove
the shell of amorphous carbon around the NDs, we demonstrate a significant
increase of the proportion of NV defects in 10-nm NDs. These results are
invaluable for further understanding, control and use of the unique properties
of negatively-charged NV defects in diamondComment: 6 pages, 4 figure
Guided assembly of nanoparticles on electrostatically charged nanocrystalline diamond thin films
We apply atomic force microscope for local electrostatic charging of oxygen-terminated nanocrystalline diamond (NCD) thin films deposited on silicon, to induce electrostatically driven self-assembly of colloidal alumina nanoparticles into micro-patterns. Considering possible capacitive, sp2 phase and spatial uniformity factors to charging, we employ films with sub-100 nm thickness and about 60% relative sp2 phase content, probe the spatial material uniformity by Raman and electron microscopy, and repeat experiments at various positions. We demonstrate that electrostatic potential contrast on the NCD films varies between 0.1 and 1.2 V and that the contrast of more than ±1 V (as detected by Kelvin force microscopy) is able to induce self-assembly of the nanoparticles via coulombic and polarization forces. This opens prospects for applications of diamond and its unique set of properties in self-assembly of nano-devices and nano-systems
Development of Diamond Tracking Detectors for High Luminosity Experiments at LHC
During 2006 detectors based on new polycrystalline CVD (pCVD) material were produced as candidates for use in LHC experiments. The first full size diamond pixel module with ATLAS specifications using a cm pCVD sample was characterized in the 2006 CERN test beam. Radiation damage studies performed outside of CERN corroborate the radiation hardness of this material. Radiation hardness studies at CERN using the highest quality diamond were deferred until 2007 due to the PS magnet problem. ATLAS, CMS, ALICE and LHCb are planning to use diamond for their beam conditions monitoring systems. Construction of the BCM system for ATLAS was completed in 2006 and the BCM modules were characterized in 2006 CERN test beams. Similar devices are under construction for the CMS, ALICE and LHCb experiments. Single-crystal CVD (scCVD) samples were produced and made available to RD42 institutes. The first scCVD diamond pixel device was constructed and tested in the 2006 CERN test beams. In this report we present the progress and work done by the RD42 collaboration on the development of CVD diamond material for radiation detectors
Proton irradiation of CVD diamond detectors for high-luminosity experiments at the LHC
CVD diamond shows promising properties for use as a position sensitive detector for experiments in the highest radiation areas at the Large Hadron Collider. In order to study the radiation hardn ess of diamond we exposed CVD diamond detector samples to 24~GeV/ and 500~MeV protons up to a fluence of . We measured the charge collection distance, the ave rage distance electron hole pairs move apart in an external electric field, and leakage currents before, during, and after irradiation. The charge collection distance remains unchanged up to and decreases by 40~\% at . Leakage currents of diamond samples were below 1~pA before and after irradiation. The particle indu ced currents during irradiation correlate well with the proton flux. In contrast to diamond, a silicon diode, which was irradiated for comparison, shows the known large increase in leakage curren t. We conclude that CVD diamond detectors are radiation hard to 24~GeV/ and 500~MeV protons up to at least without signal loss
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