I. I. Vlasov

National Research Nuclear University MEPHI, Moskva, Moscow, Russia

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Publications (121)297.3 Total impact

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    ABSTRACT: Confocal photoluminescence (PL) microscopy was used to study a distribution of negatively charged nitrogen-vacancy (NV-) defects within a surface and in a cross section of a homoepitaxial chemical vapor deposition (CVD) diamond layer intentionally grown with a nitrogen concentration close to the solubility limit. A variation in the PL intensity within the whole sample was found to exceed no more than 30% of the intensity maximum. The diamond layers with densely packed NV- arrays are a promising material platform for the design of highly sensitive magnetic field and temperature sensors, as well as for using this material in quantum optics and informatics technologies based on NV- spins.
    No preview · Article · Jan 2016 · Laser Physics
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    ABSTRACT: The processes of the synthesis of silicon-doped microcrystalline diamond films on AlN and Si substrates in microwave plasma in “methane-hydrogen-silane” mixtures were studied. It is shown that the dependence of the photoluminescence (PL) line intensity of silicon-vacancy centers in diamond (λ = 738 nm) on the silane concentration in a gas mixture passes through a maximum at SiH4/CH4 concentrations of 0.1% for Si substrates and 0.6% SiH4/CH4 for aluminum nitride substrates. It was found that such nonmonotonic variation of the PL intensity with increasing silane concentration occurs despite the unchanged growth rate of the diamond film, its structure, and phase composition in the studied silane concentration SiH4/CH4 range of 0–0.9%.
    Full-text · Article · Dec 2015 · Bulletin of the Lebedev Physics Institute
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    ABSTRACT: The first application of the high pressure-high temperature (HPHT) technique for direct production of doped ultrasmall diamonds starting from a one-component organic precursor is reported. Heavily boron-doped diamond nanoparticles with a size below 10 nm are produced by HPHT treatment of 9-borabicyclo [3,3,1]nonane dimer molecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Full-text · Article · Aug 2015 · Advanced Materials
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    ABSTRACT: Luminescence properties of nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers were investigated for the series of O-terminated composite nanodiamonds consisting of a high-pressure–high-temperature (HPHT) diamond core and a chemical-vapor-deposition (CVD) diamond outer layer of different thickness. It was found that emission of NV and SiV centers cease to “feel” the diamond surface at a distance of 12 and 4 nm, respectively, from it. This finding determines minimum sizes of O-terminated nanodiamonds in which stable single photon emitters could be formed based on NV and SiV centers. Suggested composite diamond nanostructure are optimal for design of two-color luminescent markers.The studied diamond nanoparticles present composite structure of “core-outer layer” type. The core is 20 nm HPHT diamond containing NV centers, whereas outer diamond layer containing SiV centers is formed by CVD synthesis.
    No preview · Article · Jul 2015 · Physica Status Solidi (A) Applications and Materials
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    ABSTRACT: Recently reported photoluminescent nanographene oxides (nGO), i.e. nanographene oxidised with sulfuric to nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (ND), graphene quantum dots (GQD), which all demonstrate a variety of properties that are attractive for biomedical imaging such as low toxicity and stable photoluminescence. In this study, the nGOs were organically surface-modified with poly(ethylene glycol) - poly(ethylene imine) (PEG-PEI) copolymers tagged with folic acid as affinity ligand for cancer cells expressing folate receptors. The functionalization enhanced both their cellular uptake and quantum efficiency of the photoluminescence as compared to non-modified nGOs. The nGOs exhibited an excitation dependent photoluminescence that facilitated their detection with a wide range of microscope configurations. The functionalized nGOs were non-toxic, they were retained in the stained cell population over a period of 8 days and they distributed equally between daughter cells. We have evaluated their applicability in in vitro and in vivo (chicken embryo CAM) models to visualize and track migratory cancer cells. The good biocompatibility and easy detection of the functionalized nGOs suggest that they could address the limitations faced with quantum dots and organic fluorophores in long-term in vivo biomedical imaging.
    Full-text · Article · May 2015 · Nanoscale
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    ABSTRACT: We have studied the upper limits for incorporation of nitrogen and formation of arrays of nitrogen-vacancy (NV) color centers in optical-quality single-crystalline diamond synthesized by chemical vapor deposition (CVD). The CVD diamond samples were grown in a microwave plasma in methane-hydrogen mixtures with high content (200-2000 ppm) of the nitrogen dopant in the gas mixture, and were analyzed using Raman and photoluminescence spectroscopy. From the UV absorption spectra, we established that the solubility limit for substitutional nitrogen in the studied material is close to 2·1018 cm-3 (under typical synthesis conditions), which lets us in particular form arrays of NV center with similar concentrations by means of irradiation and annealing.
    Full-text · Article · May 2015 · Journal of Applied Spectroscopy
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    ABSTRACT: Homoepitaxial single crystal diamond layers with bright photoluminescence (PL) of silicon-vacancy (SiV) color centers at 738 nm wavelength have been grown on (100) diamond substrates by a microwave plasma CVD using a controlled Si doping via adding silane to CH4H2 reaction gas mixture in the course of the deposition process. In the range of the silane concentrations SiH4/CH4 explored, from 0 to 2.4%, the SiV PL intensity shows a nonmonotonic behavior with silane addition, with a maximum at 0.6%SiH4/CH4, and a rapid PL quenching at higher Si doping. The maximum SiV concentration of ≈450 ppb in the samples has been determined from optical absorption spectra. It is found that the SiV PL intensity can strongly, an order of magnitude, increase within non-epitaxial inclusions in single crystal diamond film.
    Full-text · Article · May 2015 · Physica Status Solidi (A) Applications and Materials
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    ABSTRACT: Interactions of oxidized detonation nanodiamond and carbon dots with protic solvent molecules in suspensions of water, methanol, and isopropyl alcohol were studied by Raman and fluorescence spectroscopy. The structure of the solvent at the interface with nanoparticles and the strength of the hydrogen bonds between the functional groups on the surface of the nanoparticles and the solvent molecules depend on the type of solvent. The molecules of the solvent affect the fluorescent properties of the nanoparticles. It was found that the more intense fluorescence of nanoparticles corresponds to weaker hydrogen bonding between the surface of the carbon nanoparticles and the surrounding molecules of the solvent. The mechanism of mutual influence of the carbon nanoparticles and the solvent on the properties of each other has been suggested.Fluorescence properties of nanodiamonds in the solvents with different hydrogen bonding.
    No preview · Article · May 2015 · Physica Status Solidi (A) Applications and Materials
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    ABSTRACT: The results of the model experiment on cosmic muon radiography of a mountain with an object placed in it are presented. Scales of the difference between muon fluxes passed and not passed through the object are shown. The results for objects with densities higher and lower than that of basic ground are compared. The simulation results for the case with two detectors, which allows the determination of the object position in space, are presented. To estimate the degree of the uncertainty associated with muon rescattering in materials, events of muon of passage in iron and ground are simulated in wide energy and length ranges using the GEANT4 package. The results are presented as distributions of the number of events over the final energy and deflection angle as functions of the primary energy and the muon pathlength in a medium.
    Full-text · Article · Apr 2015 · Bulletin of the Lebedev Physics Institute
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    ABSTRACT: Nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) films with bright photoluminescence (PL) of silicon-vacancy (SiV) color centers at 738 nm have been grown using a microwave plasma CVD technique. The films were doped with Si via adding silane to CH4–H2 reaction gas mixture in the course of the deposition process. The dependence of SiV PL intensity on silane concentration in gas shows a maximum at SiH4/CH4 ratio of 0.2% and 0.6% for NCD and MCD films, respectively, the maximum intensity for MCD being an order of magnitude stronger compared with that for NCD. The PL quenching at higher CH4 addition occurs, however, no significant degradation of the film structure, such as Si-induced amorphous carbon formation, was observed within the SiH4 concentration range studied (0% – 0.9%). The higher PL efficiency of the MCD films is related to their less defective structure, as deduced from Raman spectroscopy analysis.
    Full-text · Article · Apr 2015 · Diamond and Related Materials
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    ABSTRACT: Photoluminescence spectra show that silicon impurity is present in lattice of some nanodiamond grains (ND) of various chondrites as a silicon-vacancy (SiV) defect. The relative intensity of the SiV band in the diamond-rich separates depends on chemical composition of meteorites and on size of ND grains. The strongest signal is found for the size separates enriched in small grains; thus confirming our earlier conclusion that the SiV defects preferentially reside in the smallest (less than 2 nm) grains. The difference in relative intensities of the SiV luminescence in the diamond-rich separates of individual meteorites are due to variable conditions of thermal metamorphism of their parent bodies and/or uneven sampling of nanodiamonds populations. Annealing of separates in air eliminates surface sp2-carbon, consequently, the SiV luminescence is enhanced. Strong and well-defined luminescence and absorption of the SiV defect is a promising feature to locate cold (< 250 {\deg}C) nanodiamonds in space.
    Full-text · Article · Feb 2015
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    ABSTRACT: The method of epitaxial growth of localized photoluminescence sources in the form of the ordered microcolumn diamond structures with silicon-vacancy (SiV) color centers is implemented. The process is based on diamond deposition in microwave plasma in CH4-H2 mixtures in microwells in a silicon mask on a diamond single crystal substrate, where the Si mask itself is a silicon doping source. Strong photoluminescence of SiV centers at a wavelength of 738 nm is detected; the spatial distribution of luminescence completely coincides with the synthesized structure arrangement.
    No preview · Article · Feb 2015 · Bulletin of the Lebedev Physics Institute
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    I.I. Vlasov · S.G. Lukishova · V.I. Konov

    Preview · Article · Jan 2015 · The European Physical Journal Conferences
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    ABSTRACT: Bifunctional detonation nanodiamonds (NDs) were obtained by vacuum annealing at 750 °C of NDs previously oxidized in ozone (ND-ozone). Raman investigations demonstrate a significantly higher amount of sp2 carbon compared to ND with polyfunctional surface (ND-NRI) annealed in vacuum under the same conditions. In addition to sp2 carbon caps, thermal desorption mass spectroscopy analysis revealed a higher oxygen concentration at the ND-ozone surface with abundant carbonyl and carboxylic acid anhydride groups. The supernatant of ND-ozone annealed in vacuum exhibits a positive zeta potential (+50 mV at pH 6.5), while the starting sample has a high negative zeta potential (−60 mV). This supports the oxygen hole-doping model previously proposed to explain the positive zeta potential of NDs after vacuum annealing.
    Full-text · Article · Dec 2014 · Physica Status Solidi (A) Applications and Materials
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    ABSTRACT: The principle possibility of extraction of fluorescence of nanoparticles in the presence of background autofluorescence of a biological environment using neural network algorithms is demonstrated. It is shown that the methods used allow detection of carbon nanoparticles fluorescence against the background of the autofluorescence of egg white with a sufficiently low concentration detection threshold (not more than 2 μg/ml for carbon dots 3 μg/ml and for nanodiamonds). It was also shown that the use of the input data compression can further improve the accuracy of solving the inverse problem by 1.5 times.
    Full-text · Article · Nov 2014 · Journal of Biomedical Optics
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    ABSTRACT: Nanodiamond particles are widely recognized candidates for biomedical applications due to their excellent biocompatibility, bright photoluminescence based on color centers and outstanding photostability. Recently, more complex architectures with a nanodiamond core and an external shell or nanostructure which provides synergistic benefits have been developed, and their feasibility for biomedical applications has been demonstrated. This review is aimed at summarizing recent achievements in the fabrication and functional demonstrations of nanodiamond-based composite structures, along with critical considerations that should be taken into account in the design of such structures from a biomedical point of view. A particular focus of the review is core/shell structures of nanodiamond surrounded by porous silica shells, which demonstrate a remarkable increase in drug loading efficiency; as well as nanodiamonds decorated with carbon dots, which have excellent potential as bioimaging probes. Other combinations are also considered, relying on the discussed inherent properties of the inorganic materials being integrated in a way to advance inorganic nanomedicine in the quest for better health-related nanotechnology.
    No preview · Article · Sep 2014 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: We report on fabrication of micron-scale Si-doped single crystal diamond pillars by bottom-up approach as an alternative to common reactive ion etching of diamond substrate to obtain nano-or microwires [1]. The diamond pillars have been epitaxially grown by microwave plasma CVD through windows in amorphous Si mask deposited on HPHT diamond substrate. The regular micro-scale holes were made in the mask by a Ti: sapphire laser ablation (pulse duration is 110 fs, wavelength is 400 nm). The pillars growing within the holes were automatically doped with Si as a result of the mask etching by atomic hydrogen during the process. After the mask removal the pillar arrays were produced, which showed a bright photoluminescence (PL) of SiV centers when pumped by an Ar+ laser at 488 nm wavelength. SiV zero-phonon line PL intensity of the diamond pillar at wavelength 738.6 nm normalized to its first order Raman line at 1333.6 cm-1 is 2263 times higher than that of flat diamond surface. The PL mapping for the ordered pillars realized with a confocal microscope connected to Hanbury-Brown-Twiss interferometer demonstrated high PL contrast between the pillars and the background (the substrate). In addition, the SiV PL lifetime of 0.9 ns has been evaluated upon excitation by 60 ps laser pulses at 532 nm. [1] T.
    Full-text · Conference Paper · Sep 2014
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    ABSTRACT: In this paper, we report on the bulk modifications of type IIa single-crystal diamond with visible 10-ps pulses (at λ = 532 nm) and microstructural changes characterized by the appearance of several ‘unidentifiable’ vibrational modes in the frequency range of 1000–1400 cm−1 in the Raman spectra of laser-modified diamond. It is found that the new Raman modes are strongly pronounced in the spectra of high-stress regions in immediate proximity to the bulk microstructures in the absence of the G mode at ~1580 cm−1 characteristic of the sp2 phase. The high internal stresses are determined from the splitting of the triply degenerate diamond Raman line. The revealed structure transformation is localized within a narrow bulk layer near the bulk microstructures formed, and the stress relaxation is found to result in disappearance of the detected vibrational modes in the spectra. It is suggested that the formation of bulk regions with a sp3 carbon structure consisting of Z-carbon and hexagonal diamond is responsible for the appearance of new Raman modes in the spectra of laser-modified diamond. These findings evidence that the stress-assisted formation of novel metastable carbon phases or defect structures occur in the course of bulk modification of diamond with ps-laser pulses. In addition, we report the results of simulations of internal stresses in the system ‘graphitized cylinder-in-diamond’ to show (1) the effect of the mechanical properties of laser-modified diamond on the resulting stresses and (2) formation of bulk microscopic regions with high stresses of >10 GPa, i.e., the conditions at which various sp3 carbon allotropes and defect structures become more stable than graphite.
    Full-text · Article · Jun 2014 · Applied Physics A
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    ABSTRACT: The synthesis of a new class of fluorescent carbon nanomaterials, carbon-dot-decorated nanodiamonds (CDD-ND), is reported. These CDD-NDs are produced by specific acid treatment of detonation soot, forming tiny rounded sp2 carbon species (carbon dots), 1–2 atomic layers thick and 1–2 nm in size, covalently attached to the surface of the detonation diamond nanoparticles. A combination of nanodiamonds bonded with a graphitic phase as a starting material and the application of graphite intercalated acids for oxidation of the graphitic carbon is necessary for the successful production of CDD-ND. The CDD-ND photoluminescence (PL) is stable, 20 times more intense than the intrinsic PL of well-purified NDs and can be tailored by changing the oxidation process parameters. Carbon-dot-decorated DNDs are shown to be excellent probes for bioimaging applications and inexpensive additives for PL nanocomposites.
    Full-text · Article · May 2014 · Particle and Particle Systems Characterization
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    ABSTRACT: This paper presents results of a study of adsorption properties of the original (I6) and carboxyl-modified (I6COOH) detonation nanodiamonds (DNDs) dispersed in aqueous solutions, with respect to dissolved ions: Cu2+, Pb2+, . Application of complementary spectroscopic methods allows comparative analysis of the adsorption activity of DNDs in aqueous solutions of metal salts. It was shown that both types of functionalized NDs readily adsorb nitrate ions and metal cations, and the adsorption efficiency of I6COOH is approx. three times higher than that of I6. Hypothetic mechanism of nitrate and copper ions adsorption on NDs surface is proposed.
    Full-text · Article · Feb 2014 · Journal of Alloys and Compounds

Publication Stats

1k Citations
297.30 Total Impact Points

Institutions

  • 2014-2016
    • National Research Nuclear University MEPHI
      Moskva, Moscow, Russia
  • 1997-2015
    • Russian Academy of Sciences
      • • Prokhorov General Physics Institute
      • • Institute of Chemistry
      • • A.N. Frumkin Institute of Physical chemistry and Electrochemistry
      Moskva, Moscow, Russia
  • 2009
    • Institute for Physics of Microstructures RAS
      Afonino, Nizjnij Novgorod, Russia
  • 1999
    • Max Planck Institute of Microstructure Physics
      Halle-on-the-Saale, Saxony-Anhalt, Germany