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1.
Two-photon-excited luminescence (TEL) spectra have been recorded in the blue (400–500 nm) and near-ultraviolet (300–400 nm)
ranges for diamond particles with 4 nm average size, which were obtained by detonation synthesis from explosives. The observed
TEL bands are attributed, by comparing the obtained spectra with the impurity luminescence spectra in large diamond crystals,
to N2 and N3 defects associated with the presence of nitrogen impurities in diamond. The TEL spectra presented are found to have certain
distinguishing features: short-wavelength shift of the maximum and changes in the shape and width of the spectral bands for
ultradispersed diamond compared with the spectrum in bulk crystals.
Fiz. Tverd. Tela (St. Petersburg) 41, 1110–1112 (June 1999) 相似文献
2.
A. N. Obraztsov I. Yu. Pavlovskii H. Okushi H. Watanabe 《Physics of the Solid State》1997,39(10):1594-1598
Photoacoustic spectroscopy is used to study optical absorption in diamond powders and polycrystalline films. The photoacoustic
spectra of diamond powders with crystallite sizes in the range from ∼100 μm to 4 nm and diamond films grown by chemical vapor deposition (CVD) had a number of general characteristic features corresponding
to the fundamental absorption edge for light with photon energies exceeding the width of the diamond band gap (∼5.4 eV) and
to absorption in the visible and infrared by crystal-structure defects and the presence of non-diamond carbon. For samples
of thin (∼10 μm) diamond films on silicon, the photoacoustic spectra revealed peculiarities associated with absorption in the silicon substrate
of light transmitted by the diamond film. The shape of the spectral dependence of the amplitude of the photoacoustic signal
in the ultraviolet indicates considerable scattering of light specularly reflected from the randomly distributed faces of
the diamond crystallites both in the polycrystalline films and in the powders. The dependence of the shape of the photoacoustic
spectra on the light modulation frequency allows one to estimate the thermal conductivity of the diamond films, which turns
out to be significantly lower than the thermal conductivity of single-crystal diamond.
Fiz. Tverd. Tela (St. Petersburg) 39, 1787–1791 (October 1997) 相似文献
3.
Liang Xu Shuankui Li Zhiguo Wu Huajun Li De Yan Chunyu Zhang Pengju Zhang Pengxun Yan Xudong Li 《Applied Physics A: Materials Science & Processing》2011,103(1):59-65
Nanotip arrays of amorphous carbon with embedded hexagonal diamond nanoparticles were prepared at room temperature for use
as excellent field emitters by a unique combination of anodic aluminum oxide (AAO) template and filtered cathodic arc plasma
(FCAP) technology. In order to avoid nanopore array formation on the AAO surface, an effective multi-step treatment employing
anodization and pore-widening processes alternately was adopted. The nanotips were about 100 nm in width at the bottom and
150 nm in height with density up to 1010 cm−2. Transmission electron microscopy investigation indicates that many nanoparticles with diameters of about 10 nm were embedded
in the amorphous carbon matrix, which was proved to be hexagonal diamond phase by Raman spectrum and selected-area electron
diffraction. There is no previous literature report on the field emission properties of hexagonal diamond and its preparation
at room temperature under high-vacuum condition. The nanotip arrays with hexagonal diamond phase exhibit a low turn-on field
of 0.5 V/μm and a threshold field of 3.5 V/μm at 10 mA/cm2. It is believed that the existence of hexagonal diamond phase has improved the field emission properties. 相似文献
4.
Sergei M. Pimenov Igor I. Vlasov Andrey A. Khomich Beat Neuenschwander Martin Muralt Valerio Romano 《Applied Physics A: Materials Science & Processing》2011,105(3):673-677
Arrays of through laser-graphitized microstructures have been fabricated in type IIa single-crystal 1.2-mm-thick diamond plates
by multipulse laser irradiation with 10-ps pulses at λ=532 nm wavelength. Raman and photoluminescence (PL) spectroscopy studies of the bulk microstructures have evidenced the diamond
transformation to amorphous carbon and graphitic phases and the formation of radiation defects pronounced in the PL spectra
as the self-interstitial related center, the 3H center, at 504 nm. It is found that the ultrafast-laser-induced structural
modifications in the bulk of single-crystal diamond plates occur along {111} planes, known as the planes of the lowest cleavage
energy and strength in diamond. 相似文献
5.
V. V. Brazhkin A. G. Lyapin R. N. Voloshin S. V. Popova Yu. A. Klyuev A. M. Naletov S. C. Bayliss A. V. Sapelkin 《JETP Letters》1999,69(11):869-875
The results of an investigation of the transformation of C60 fullerite to diamond under pressure through intermediate three-dimensionally polymerized and amorphous phases are reported.
It is found that treatment of fullerite C60 at pressures 12–14 GPa and temperatures ∼1400°C produces a nanocrystalline graphite-diamond composite with a concentration
of the diamond component exceeding 50%. At lower temperatures (700–1200°C) nanocomposites consisting of diamondlike (sp
3) and graphitic (sp
2) amorphous phases are formed. The nanocomposites obtained have extremely high mechanical characteristics: hardness comparable
to that of best diamond single crystals and fracture resistance two times greater than that of diamond. Mechanisms leading
to the transformation of C60 fullerite into diamond-based nanocomposites and the reasons for the high mechanical characteristics of these nanocomposites
are discussed.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 822–827 (10 June 1999) 相似文献
6.
Filler-matrix thermal boundary resistance of diamond-copper composite with high thermal conductivity 总被引:1,自引:0,他引:1
A composite material with a high thermal conductivity is obtained by capillary infiltration of copper into a bed of diamond
particles of 400 μm size, the particles having been pre-coated with tungsten. The measured thermal conductivity of the composite
decreases from 910 to 480 W m−1 K−1 when the coating thickness is increased from 110 to 470 nm. Calculations of the filler/matrix thermal boundary resistance
R and the thermal conductivity of the coating layer λ
i
using differential effective medium, Lichtenecker’s and Hashin’s models give similar numerical values of R and λ
i
≈ 1.5 W m−1 K−1. The minimal thickness of the coating h ∼ 100 nm necessary for ensuring production of a composite while maximizing its thermal conductivity, is of the same order
as the free path of the heat carriers in diamond (phonons) and in copper (electrons). The heat conductance of the diamond/tungsten
carbide coating/copper interface when h is of this thickness is estimated as (0.8–1) × 108 W m−2 K−1 and is at the upper level of values characteristic for perfect dielectric/metal boundaries. 相似文献
7.
A. N. Obraztsov I. Yu. Pavlovskii V. G. Ral’chenko H. Okushi H. Watanabe 《Technical Physics》1999,44(4):438-442
A new method of determining the heat-conducting properties of diamond films is proposed, based on the photoacoustic effect.
This method is used to study diamond polycrystalline films grown on silicon by chemical vapor deposition in a microwave discharge
plasma. The thermal conductivity obtained was approximately half that for single-crystal diamond.
Zh. Tekh. Fiz. 69, 97–101 (April 1999) 相似文献
8.
Feoktistov N. A. Sakharov V. I. Serenkov I. T. Tolmachev V. A. Korkin I. V. Aleksenskii A. E. Vul’ A. Ya. Golubev V. G. 《Technical Physics》2011,56(5):718-724
The aerosol deposition of detonation nanodiamonds (DNDs) on a silicon substrate is comprehensively studied, and the possibility
of subsequent growth of nanocrystalline diamond films and isolated particles on substrates coated with DNDs is demonstrated.
It is shown that a change in the deposition time and the weight concentration of DNDs in a suspension in the range 0.001–1%
results in a change in the shape of DND agglomerates and their number per unit substrate surface area N
s
from 108 to 1011 cm−2. Submicron isolated diamond particles are grown on a substrate coated with DND agglomerates at N
s
≈ 108 cm−2 using microwave plasma-enhanced chemical vapor deposition. At N
s
≈ 1010 cm−2, thin (∼100 nm) nanodiamond films with a root-mean-square surface roughness less than 15 nm are grown. 相似文献
9.
The pressure dependence of lattice constants of 13C-enriched diamond and diamond of natural isotopic composition have been studied by using x-ray synchrotron radiation and
the imaging plate technique. The compression curves reveal features which indicate an inversion of the isotope effect at high
pressure.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 2, 73–77 (25 January 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
10.
Nanostructured nonstoichiometric vanadium carbide VC0.87 was obtained in powdered form using the ordering effect. The composition, structure, and properties of the carbide were studied
by chemical and thermogravimetric analysis, gas chromatography, x-ray diffraction, optical and electronic microscopy, electron-positron
annihilation, magnetic susceptibility, and microhardness methods. Nanostructured vanadium carbide VC0.87 possesses the crystal structure of the cubic ordered phase V8C7 with space group P4332. Vanadium carbide nanocrystallites are shaped in the form of 400–600 nm in diameter and 15–20 nm thick curved petals. The
surface layer of the nanocrystallites contains defects of the vacancy agglomerate type. The microhardness of vanadium carbide,
obtained by vacuum sintering of VC0.87 nanopowder was 60–80 GPa, which is 3–4 times greater than the microhardness of coarse-grained vanadium carbide with the same
composition and close to the hardness of diamond.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 6, 436–442 (25 March 1999) 相似文献
11.
Swee Chuan Tjin Jianzhong Hao Yu-Zhi Lam Yoong Ching Ho Beng Koon Ng 《Fiber and Integrated Optics》2013,32(1):59-69
In the present investigation, a Q-switched Nd:YAG laser is used to study the various aspects of diamond processing for fabricating integrated optic and UV optoelectronic devices. Diamond is a better choice of substrate compared to silicon and gallium arsenide for the fabrication of waveguides to perform operations such as modulation, switching, multiplexing, and filtering, particularly in the ultraviolet spectrum. The experimental setup of the present investigation consists of two Q-Switched Nd:YAG lasers capable of operating at wavelengths of 1064 nm and 532 nm. The diamond cutting is performed using these two wavelengths by making the “V”-shaped groove with various opening angle. The variation of material loss of diamond during cutting is noted for the two wavelengths. The cut surface morphology and elemental and structural analysis of graphite formed during processing in both cases are compared using scanning electron microscopy (SEM) and laser Raman spectroscopy. Both the Q-Switched Nd:YAG laser systems (at 1064 nm and 532 nm) show very good performance in terms of peak-to-peak output stability, minimal spot diameter, smaller divergence angle, higher peak power in Q-switched mode, and good fundamental TEM 00 mode quality for processing natural diamond stones. Less material loss and minimal micro cracks are achieved with wavelength 532 nm whereas a better diamond cut surface is achieved with processing at 1064 nm with minimum roughness. 相似文献
12.
Adriana Faria Azevedo F. A. Souza P. Hammer M. R. Baldan N. G. Ferreira 《Journal of nanoparticle research》2011,13(11):6133-6139
The surface properties of boron-doped nanocrystalline diamond films treated with H2 plasma was investigated in regard to their electrochemical response for phenol oxidation. The surface of these films is relatively
flat formed by crystallites with sizes of about 40 nm. X-ray photoelectron spectroscopy analyses showed that electrode surface
has a high amount of C–H bonds. This behavior is in agreement with Mott-Schottky plot measurements concerning the flat band
potential that presented a value as expected for hydrogenated diamond surface. This electrode presented the phenol detection
limit of 0.08 mg L−1 for low phenol concentrations from 40 to 250 μmol L−1. 相似文献
13.
A. E. Aleksenskii M. V. Baidakova A. Ya. Vul’ V. I. Siklitskii 《Physics of the Solid State》1999,41(4):668-671
A model describing the structure of diamond nanoclusters produced by explosive shocks is proposed. The model is based on experimental
data obtained from x-ray diffraction and small-angle x-ray scattering. This model considers the diamond nanocluster as a crystalline
diamond core coated by a carbon shell having a fractal structure. The shell structure depends both on the cooling kinetics
of the detonation products and on the method used to extract from them the diamond fraction.
Fiz. Tverd. Tela (St. Petersburg) 41, 740–743 (April 1999) 相似文献
14.
15.
V. D. Blank V. M. Levin V. M. Prokhorov S. G. Buga G. A. Dubitskii N. R. Serebryanaya 《Journal of Experimental and Theoretical Physics》1998,87(4):741-746
The elastic properties of C60 fullerite samples synthesized under pressure P=13.0 GPa at high temperatures were investigated using acoustic microscopy. The velocities of longitudinal (c
L=17–26 km/s) and transverse (c
T=7.2–9.6 km/s) elastic waves in the samples were measured. It was established that the longitudinal sound velocity of ultrahard
fullerites is higher than that of any other known solid. The bulk modulus of these ultrahard samples is higher than that of
diamond and reaches a value greater than 1 TPa. The high bulk modulus, the relatively large shear moduli, and the substantial
Poisson ratio indicate that the structure of the ultrahard fullerites is fundamentally different from that of diamond.
Zh. éksp. Teor. Fiz. 114, 1365–1374 (October 1998) 相似文献
16.
N. A. Borisevich S. A. Bagnich T. F. Raichenok V. N. Knyukshto A. V. Baranovskii V. N. Zhabinskii 《Journal of Applied Spectroscopy》2008,75(2):187-191
Biologically active brassinosteroid 24-epicastasterone, ring B of which contains a C=O group and has the nπ*-configuration
for a low-lying electronic excited state, exhibits rapid fluorescence. The wavelengths of the fluorescence maxima of the steroid
dissolved in hexane and acetonitrile are equal to 332 and 394 nm, respectively. The fluorescence lifetime of the steroid dissolved
in acetonitrile is τ = 9.9 nsec. Solutions of 24-epibrassinolide do not luminesce. The long-wavelength electronic absorption
band λmaxabs = 340 nm in the absorption spectrum of an ethanol solution of model compound 2, ring D of which contains a C=O group π*-conjugated with the C=C double bond of ring C, like in the spectrum of the steroid,
has a low extinction coefficient. An ethanol solution of 2 does not fluoresce. 24-Epicastasterone at 77 K in ethanol solution exhibits phosphorescence with λmaxphos = 447 nm. The phosphorescence decay is exponential with τ = 0.79 msec. Compound 2 also phosphoresces. The phosphorescence spectrum of its ethanol solution has a maximum at 490 nm. The phosphorescence decay
is nonexponential in the early stage. The phosphorescence lifetime is 25 msec in the exponential decay region.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 182–186, March–April, 2008. 相似文献
17.
The photophysics and cyclic voltammetry of two novel phosphorescent thiones, 2,2-dimethyl-indan-1-one-3-thione (DMIKT) and 2,2-dimethyl-indan-1,3-dithione (DMIDT), and three known phosphorescent thiones, 4H-pyran-4-thione (PT), 4H-1-benzopyran-4-thione (BPT) and 2,2-dimethylindan-1-thione (DMIT), have been characterised and compared. The phosphorescence emission of DMIT, DMIKT and DMIDT extends from the red into the near-IR spectral region. The additional carbonyl or thione group of DMIKT and DMIDT causes a significant shift in the emission maxima to 680 nm compared to that of DMIT, at 637 nm, in perfluorinated hydrocarbons. In acetonitrile the emission maxima of DMIKT and DMIDT are at 696 and 706 nm, respectively, and the spectra show vibronic bands which extend out beyond 850 nm. There is a significant
reduction in triplet lifetime along this series (from 44 (±2) μs (DMIT) to 10 ((±0.8) μs (DMIKT) in perfluorinated solvents, and 8.6 (±0.5) (DMIT), 1.3 (±0.5) (DMIKT) and 0.35 (±0.07) μs (DMIDT) in acetonitrile), as well as a reduction in the rate constant for ground-state quenching of the triplet, (from 9.8 ((±0.9)
to 3.5 ((±0.6) and 1.3 ((±0.2) × 109 mol−1 dm3 s−1 for the same compounds). The addition of the C=O or C=S groups also causes a decrease in phosphorescence quantum yield with
the highest emission quantum yield obtained for DMIT (Φ
P = 0.149 (±0.015)). Electrochemical studies show that while PT and BPT exhibit irreversible redox behaviour, DMIT, DMIKT and DMIDT all show at least one reversible reduction wave attributed to a one-electron process centred on the C=S moiety. The suitability
of these lumophores for use in OLEDs is discussed. 相似文献
18.
Laser polishing of diamond plates 总被引:5,自引:0,他引:5
S.M. Pimenov V.V. Kononenko V.G. Ralchenko V.I. Konov S. Gloor W. Lüthy H.P. Weber A.V. Khomich 《Applied Physics A: Materials Science & Processing》1999,69(1):81-88
Results are reported on laser polishing of 150–400-μm-thick free-standing diamond films with either a copper vapor laser (510 nm
wavelength) or an ArF excimer laser (193 nm wavelength). Studies were focused on three particular goals. First, we aimed at
a choice of optimum conditions for laser polishing of thick diamond films. It was shown that the laser polishing conditions
and the resulting surface roughness were controlled by varying the angle of incidence of a scanning laser beam and by polishing
time. Second, the laser ablation technique was applied to remove a defective layer from the “substrate” side of the diamond
plates in order to reduce optical losses due to absorption in this layer. Third, the structure of the laser-graphitized diamond
surface was studied using UV, visible, and IR optical spectroscopy techniques in the course of the “step-by-step” oxidative
removal of the graphitic layer with increasing temperature of the oxidation in ambient air. Once the graphitic layer was removed,
the optical transmission in the UV-visible-IR spectral range of the diamond films polished under optimum conditions was measured
and compared with the optical transmission of the mechanically polished diamond films. It was shown that the optical quality
(in the long-wave infrared region) of the laser-polished diamond plates was sufficient to reach the transmittance value very
close to the theoretical limit.
Received: 20 October 1998 / Accepted: 8 March 1999 / Published online: 5 May 1999 相似文献
19.
Field emission in diamond and graphite-like polycrystalline films is investigated experimentally. It is shown that the emission
efficiency increases as the nondiamond carbon phase increases; for graphite-like films the threshold electric field is less
than 1.5 V/μm, and at 4 V/μm the emission current reaches 1 mA/cm2, while the density of emission centers exceeds 106 cm−2. A general mechanism explaining the phenomenon of electron field emission from materials containing graphite-like carbon
is proposed.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 56–60 (10 July 1998) 相似文献
20.
Transient nutation ESR spectroscopy has been used to study the broadening of isolated lines in the triplet of P1 nitrogen centers in disperse synthetic diamond bombarded by electrons and annealed at 670–1070 K. On the basis of measurements
of the spin-spin relaxation time, it was established that at nitrogen concentrations up to 1.2×1019 cm−3 the homogeneous line width is caused by dipole interaction between the nitrogen atoms and exchange interactions make no contribution.
Fiz. Tverd. Tela (St. Petersburg) 40, 1235–1237 (July 1998) 相似文献