SiV Color Centers in Si-Doped Isotopically Enriched 12C and 13C CVD Diamonds
The effect of isotopic modification of diamond lattice on photoluminescence (PL) and optical absorption spectra of ensembles of SiV− centers was studied. Thin epitaxial diamond layers were grown by a microwave plasma CH4/H2 mixtures using methane enriched to 99.96% for either 12C or 13C isotopes, while the Si doping was performed by adding a small percentage of silane SiH4 into the plasma. Temperature dependent SiV−ZPL spectra in absorption were measured at 3–80 K to monitor the evolution of the ZPL fine structure. It is found that the SiV− ZPL at 736.9 nm observed in PL for 12C diamond at T = 5 K, exhibits a blue shift of 1.78 meV, to 736.1 nm in 13C diamond matrix. Narrow ZPL with the width (FWHM) of 0.09 meV (21 GHz) was measured in absorption spectra at T = 3–30 K in the Si‐doped 13C diamond. Besides the charged SiV− center, the absorption of the neutral SiV0 defect at 946 nm wavelength has also been detected. From changes observed in SiV− phonon band structure in PL with isotopic modification, the band at 64 meV was confirmed to be a local vibration mode (LVM) involving a Si atom.
We report on the quantum yield (eta) and decay time (tau) measurements at room temperature for the bright red-orange (602 nm) luminescence from new germanium-vacancy (Ge-V) centers in nano- and microcrystalline diamonds synthesized at high pressure and high temperature. The values eta = 3 +/- 1% and tau = 6.2 +/- 0.2 ns were found. The Stokes shift measured as the energy difference between the maxima of the luminescence and luminescence excitation spectra is negligible. The relative intensity of the zero-phonon line constitutes up to 70% from the total intensity of the luminescence. Results of our ab initio DFT calculations for the ground-state electronic and vibrational structure of (Ge-V)(-) in diamond are presented and discussed.
Hirashasan is the term used for governance of diamond mining and trade – with a small bureaucracy and an exclusive set of rules and regulations – by the district administration of Panna in the state of Madhya Pradesh in India. Diamond mining in Panna encompasses diverse extractive practices that range from fully mechanised large-scale mining operations owned by the state, to small-scale and semi-mechanised mining carried out by farmers and landowners in groups, to individuals carrying out seasonal and part-time mining of diamonds in an artisanal manner. Based on an ethnographic study was undertaken from September 2016 to April 2017, we argue that Hirashasan has created an “extractive assemblage” that comprises four genres of mining and production systems: large-scale, small-scale, licensed artisanal and unlicensed artisanal. This assemblage is a product of historical, cultural and geographical contingencies as much as place-specificities, and does not lend itself to a single mode of governance. Mineral resource governance in a particular place, therefore, necessitates understanding and internalising the variegated and pluri-form extractive assemblages, such as that of the diamond economy in Panna.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
By using superconducting quantum interference device (SQUID) magnetometry, we investigated anisotropic high-field (H less than or similar to 7T) low-temperature (10 K) magnetization response of inhomogeneous nanoisland FeNi films grown by rf sputtering deposition on Sitall (TiO2) glass substrates. In the grown FeNi films, the FeNi layer nominal thickness varied from 0.6 to 2.5 nm, across the percolation transition at the d(c) similar or equal to 1.8 nm. We discovered that, beyond conventional spin-magnetism of Fe21Ni79 permalloy, the extracted out-of-plane magnetization response of the nanoisland FeNi films is not saturated in the range of investigated magnetic fields and exhibits paramagnetic-like behavior. We found that the anomalous out-of-plane magnetization response exhibits an escalating slope with increase in the nominal film thickness from 0.6 to 1.1 nm, however, it decreases with further increase in the film thickness, and then practically vanishes on approaching the FeNi film percolation threshold. At the same time, the in-plane response demonstrates saturation behavior above 1.5-2T, competing with anomalously large diamagnetic-like response, which becomes pronounced at high magnetic fields. It is possible that the supported-metal interaction leads to the creation of a thin charge-transfer (CT) layer and a Schottky barrier at the FeNi film/Sitall (TiO2) interface. Then, in the system with nanoscale circular domains, the observed anomalous paramagnetic-like magnetization response can be associated with a large orbital moment of the localized electrons. In addition, the inhomogeneous nanoisland FeNi films can possess spontaneous ordering of toroidal moments, which can be either of orbital or spin origin. The system with toroidal inhomogeneity can lead to anomalously strong diamagnetic-like response. The observed magnetization response is determined by the interplay between the paramagnetic-and diamagnetic-like contributions.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.