Search results for "diamond"
showing 10 items of 234 documents
Differentiation of natural and synthetic gem-quality diamonds by luminescence properties
2003
Abstract Laser-excited time-resolved and UV-excited static photoluminescence (PL) as well as cathodoluminescence (CL) techniques were applied to identify the origin of diamonds. Samples represented natural faced and rough diamonds from diamond market and different kimberlites as well as the most common high pressure–high temperature (HPHT) and as-grown synthetic diamonds. The time-resolved PL spectra of natural and synthetic diamonds display clear mutual differences. The static PL and CL spectra of natural diamonds revealed emission bands caused by complex nitrogen–vacancy (N–V)-aggregates whereas the bands of synthetic diamonds reflect simple N–V-aggregates and nickel-containing defects. T…
Diamond magnetometer enhanced by ferrite flux concentrators
2020
Magnetometers based on nitrogen-vacancy (NV) centers in diamond are promising room-temperature, solid-state sensors. However, their reported sensitivity to magnetic fields at low frequencies (<1 kHz) is presently >10 pT s^{1/2}, precluding potential applications in medical imaging, geoscience, and navigation. Here we show that high-permeability magnetic flux concentrators, which collect magnetic flux from a larger area and concentrate it into the diamond sensor, can be used to improve the sensitivity of diamond magnetometers. By inserting an NV-doped diamond membrane between two ferrite cones in a bowtie configuration, we realize a ~250-fold increase of the magnetic field amplitude wi…
Noncovalent force spectroscopy using wide-field optical and diamond-based magnetic imaging
2019
A realization of the force-induced remnant magnetization spectroscopy (FIRMS) technique of specific biomolecular binding is presented where detection is accomplished with wide-field optical and diamond-based magnetometry using an ensemble of nitrogen-vacancy (NV) color centers. The technique may be adapted for massively parallel screening of arrays of nanoscale samples.
Two-dimensional nuclear magnetic resonance spectroscopy with a microfluidic diamond quantum sensor
2019
Quantum sensors based on nitrogen-vacancy centers in diamond have emerged as a promising detection modality for nuclear magnetic resonance (NMR) spectroscopy owing to their micron-scale detection volume and non-inductive based detection. A remaining challenge is to realize sufficiently high spectral resolution and concentration sensitivity for multidimensional NMR analysis of picoliter sample volumes. Here, we address this challenge by spatially separating the polarization and detection phases of the experiment in a microfluidic platform. We realize a spectral resolution of 0.65 +/- 0.05 Hz, an order-of-magnitude improvement over previous diamond NMR studies. We use the platform to perform …
Continuously tunable diamond Raman laser for resonance laser ionization.
2019
We demonstrate a highly efficient, tunable, ∼5 GHz line- width diamond Raman laser operating at 479 nm. The diamond laser was pumped by a wavelength-tunable intra- cavity frequency-doubled titanium sapphire (Ti:Sapphire) laser operating at around 450 nm, at a repetition rate of 10 kHz with a pulse duration of 50 ns. The Raman reso- nator produced a continuously tunable output with high stability, high conversion efficiency (28%), and beam quality (M$^{2}$ <1.2). We also demonstrate that the linewidth and tunability of the pump laser is directly transferred to the Stokes output. Our results show that diamond Raman lasers offer great potential for spectroscopic applications, such as resonance…
Colloidal nanoparticle sorting and ordering on anodic alumina patterned surfaces using templated capillary force assembly
2017
Abstract A new, robust technique of size-selective nanoparticle ordering on porous anodized aluminum oxide (PAAO) templates is presented. Simultaneous particle sorting and array formation is achieved for the first time using a polydisperse suspension of irregularly shaped diamond nanocrystals. The array parameters can be tuned through a balance of evaporation driven particle flux, capillary, electrostatic, and adhesion forces, which are influenced by the asperities of the surface during the capillary and convective assembly dip-coating process. The resulting structures are dense (lower limit approximately 50 nm center separation), isolated (non-touching) nanoparticle arrays with a size dist…
Diamond Films as Support for Electrochemical Systems for Energy Conversion and Storage
2019
Many efforts have been dedicated to develop and study different catalysts supported materials for energy storage and conversion. Polymer electrolyte membranes (PEM) and capacitors have been topics of special interest for the scientific community, then, the research to find excellent catalyst-supports has constantly increased. The use of conductive diamond films has been proposed due to their mechanical and chemical stability properties. In this context, the application of BDD-catalyst surfaces for PEM fuel cells as well as the production of electrochemical capacitors using BDD materials have been summarized and discussed in this chapter.
Ab initio studies on the lattice thermal conductivity of silicon clathrate frameworks II and VIII
2016
The lattice thermal conductivities of silicon clathrate frameworks II and VIII are investigated by using ab initio lattice dynamics and iterative solution of the linearized Boltzmann transport equation(BTE) for phonons. Within the temperature range 100-350 K, the clathrate structures II and VIII were found to have lower lattice thermal conductivity values than silicon diamond structure (d-Si) by factors of 1/2 and 1/5, respectively. The main reason for the lower lattice thermal conductivity of the clathrate structure II in comparison to d-Si was found to be the harmonic phonon spectra, while in the case of the clathrate structure VIII, the difference is mainly due to the harmonic phonon spe…
Surface morphology and grain analysis of successively industrially grown amorphous hydrogenated carbon films (a-C:H) on silicon
2015
Abstract Silicon (1 0 0) has been gradually covered by amorphous hydrogenated carbon (a-C:H) films via an industrial process. Two types of these diamond-like carbon (DLC) coatings, one more flexible (f-DLC) and one more robust (r-DLC), have been investigated. Both types have been grown by a radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique with acetylene plasma. Surface morphologies have been studied in detail by atomic force microscopy (AFM) and Raman spectroscopy has been used to investigate the DLC structure. Both types appeared to have very similar morphology and sp 2 carbon arrangement. The average height and area for single grains have been analyzed for al…
Electrochemical treatment of real wastewater. Part 1: Effluents with low conductivity
2018
Abstract The treatment of a real wastewater characterized by low conductivity was performed by anodic oxidation at boron doped diamond (BDD) in both conventional and microfluidic cells. The electrolyses carried out in conventional cells without supporting electrolyte were characterized by very high TOC removals but excessively high energetic consumptions and operating costs. The addition of sodium sulphate, as supporting electrolyte, allowed to strongly reduce the cell potentials and consequently the energetic consumptions and the operating costs. However, under various operating conditions, the addition of Na2SO4 caused a lower removal of the TOC. The best results in terms of both TOC remo…