共查询到20条相似文献,搜索用时 31 毫秒
1.
A. K. Shuaibov L. L. Shimon A. I. Dashchenko A. I. Minya 《Journal of Applied Spectroscopy》1999,66(1):1-6
We present the results of investigation into radiation of a pulsed transverse discharge in neon at a pressure of 10–200 kPa.
Survey spectra of plasma radiation, time characteristics of radiation, and the effect of small impurities of water vapors
and air on the optical characteristics of a neon plasma were studied. We show that at a pressure of residual gases at a level
of 10 Pa intense OH*, NO*, and N
*
2
bands are observed in radiation of the plasma of a nanosecond transverse discharge in Ne against the background of continuous
plasma radiation, and in the spectral region with λ>400 nm radiation was observed on the Hβ 486.1 nm and NeI 585.3 nm lines, and (when P≥100 kPa) on the line at the 3s–3p-transitions of a Ne atom. The radiation intensity
of the third continuum of neon increases with pressure and with energy contribution to plasma, with its maximum being located
in the VUV spectral region (λ
max
<200 nm).
To whom correspondence should be adressed.
Uzhgorod State University, 46, Pidgirna St., Uzhgorod, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66,
No. 1, pp. 5–10, January–February, 1999. 相似文献
2.
In a suitable pH buffer solutions, sodium diethyldithiocarbamate (DDTC) reacts with some divalence metal ions M(II) to form
(M–DDTC)
n
chelate complex nanoparticles, which exhibit different luminescence properties. There is a strongest luminescence peak at
470 nm for the Co(II)–DDTC system, three peaks at 330, 470, and 630 nm for the Cu(II)–DDTC system, three peaks at 420, 470,
and 630 nm for the Cd(II)–DDTC system, four peaks at 350, 400, 435, and 470 nm for the Ni(II)–DDTC system, two peaks at 408
and 470 nm for the Pb(II)–DDTC system, two peaks at 415 and 470 nm for the Fe(II)–DDTC system. The different luminescence
properties of (M–DDTC)
n
chelate complex nanoparticles was explained. Under the optimal conditions, the luminescence intensity of (Co–DDTC)
n
chelate complex nanoparticles at 470 nm (F
470 nm) is linear to Co(II) concentration in the range of 0.012–1.44 μg/mL. The detection limit is 0.0023 μg/mL. A novel luminescence method has been proposed for the determination of cobalt in Vitamin B12 samples, with satisfactory results. 相似文献
3.
A nuclear matter test has been conducted on a separable non-localN-N interaction proposed by Sirohi and Srivastava. The potential had been constructed by fitting the phase-shifts. The results
obtained compare with those obtained by Tabakin in each partial wave. The binding energy per particle and the symmetry energy
coefficient obtained are 19.4 MeV and 66.5 MeV respectively atk
F=1.65 fm−1, while the best estimated values for these quantities are 16 MeV and 30–35 MeV atk
F=1.5 fm−1. Single particle potential generated out of this NLSI has in general the same shape as the one obtained through Tabakin potential.
Finally as a test of non-locality the integrated photoabsorption cross-section parameterh has been calculated and the value of 1.03 agrees with other reported values. 相似文献
4.
M. Inui Y. Kajihara K. Matsuda S. Hosokawa K. Tamura M. Yao Y. Tsuchiya D. Ishikawa S. Tsutsui A. Q. R. Baron 《The European physical journal. Special topics》2011,196(1):167-174
Liquid As2Se3 undergoes the semiconductor-metal transition with increasing temperature when pressure is applied to avoid evaporation of
the liquid. To investigate the atomic dynamics of liquid As2Se3, we have carried out inelastic x-ray scattering experiments of this system at 1073 K and 6 MPa and obtained the dynamic structure
factor S(Q,E), from approximately 1.6 nm−1 to 11 nm−1, where Q and E are momentum and energy transfer, respectively. The excitation energy in the semiconducting state at 1073 K disperses as
fast as the ultrasonic sound velocity at Q < 2.5 nm−1 but at Q > 2.9 nm−1 it disperses approximately 1.8 times faster. We analyzed S(Q,E) at 1073 K using a simple viscoelastic model and discussed Q dependence of the propagation of the acoustic mode. 相似文献
5.
O. L. Kheifets A. L. Filippov N. V. Melnikova A. N. Babushkin 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(3):385-388
The effect of static pressure on the electric properties of vitreous materials Cu1 − x
Ag
x
GeAsSe3, where x = 0.95, 0.9, and 0.85 is studied. The pressure dependences of impedance and dielectric loss tangent at pressures 15–45 GPa
are analyzed. The ranges of substantial changes in the electrical properties of the samples are found. 相似文献
6.
H. Lefèvre 《Applied Physics A: Materials Science & Processing》1980,22(1):15-22
Deep-level profiles were measured radially acrossn-type FZ silicon wafers containing A-swirl defects by applying DLTS to an array of Schottky contacts. The trapparameters were
obtained very accurately using a computer-fit procedure for the full DLTS peaks. Two acceptor levels atE
c
−0.49 eV (σ
n
=6.6×10−16cm2) andE
c
−0.07 eV (σ
n
=4.6×10−16cm2) were observed, which varied oppositely to the A-swirl defect density. At short ranges (1–2mm) the trap concentration-profile
was smeared out and did not follow the strong fluctuations in the etch pattern. Both levels were measured together with the
same concentration. The profiles indicate outdiffusion. A level atE
c
−0.14 eV (σ
n
=1.1×10−16cm2) was not related to A-swirl defects. A level atE
c
−0.11 eV (σ
n
=1.1×10−15cm2) was only detected in one ingot.
The properties of the deep level atE
c
−0.49 eV are discussed in the light of published DLTS results reported for γ-irradiation, laser annealing after self-implantation,
annealing under pressure and oxidation of silicon samples. It is concluded, that this level is related to interstitial silicon
rather than to an impurity. 相似文献
7.
Interference is investigated between a stationary cylinder wake and that of a downstream streamwise oscillating cylinder.
Experiments were carried out in a water tunnel. A laser-induced fluorescence technique was used to visualize the flow structure
behind two inline circular cylinders of identical diameterd. The downstream cylinder was forced to oscillate harmonically at the amplitude of 0.5d and the frequency ratiof
e
f
s=1.8, wheref
e is the oscillation frequency of the downstream cylinder andf
s is the vortex shedding frequency from an isolated stationary cylinder. The investigation was conducted for the cylinder center-to-center
spacingL/d=2.5 ∼ 4.5. Two flow regimes have been identified, i.e. the ‘single-cylinder shedding regime’ atL/d<-3.5 and the ‘two-cylinder shedding regime’ atL/d>3.5. At smallL/d, the upstream cylinder does not appear to shed vortices; vortices are symmetrically formed behind the downstream cylinder
as a result of interactions between the shear layers separated from the upstream cylinder and the oscillation of the downstream
cylinder. This is drastically different from that behind two stationary cylinders atL/d<-3.5, where vortices are shed alternately from the downstream cylinder only. AtL/d=4.5, both upstream and downstream cylinders shed vortices. This is true with or without the oscillation of the downstream
cylinder. The flow structure is now totally different from that atL/d=3.5. The vortices are shed alternately from the upstream cylinder; a staggered spatial arrangement of vortices occurs behind
the downstream cylinder. 相似文献
8.
本文以自制Ge20Sb15Se65硫系玻璃为基质材料,设计一种正八边形结构色散平坦型中红外硫系光子晶体光纤,并采用多极法对其中红外色散和传输特性进行数值研究.结果表明:控制该光纤占空比(d/Λ)在0.323—0.367之间,其色散及传输特性在3—5μm范围内可调.当孔间距Λ=3.4μm,孔直径d=1.1μm时,光纤在4.1—4.9μm波段的色散值在0.8—0.8 ps·nm 1·km 1波动,且具备单模低损耗传输(Loss0.049dB/m),小模场面积(Aeff8.46μm2)特性,适合于中红外非线性应用领域. 相似文献
9.
Summary The structure of water in water/AOT/n-heptane reverse micelles has been studied as a function of the [H2O]/[AOT] ratio (W) by using the absorption IR due to O−H stretching modes in the 3800–3000 cm−1 range. The results show that the IR spectra can be expressed as a sum of contributions from bound- and bulk-like water. The
fraction of water in the two ?regions? within the water pool was evaluated as a function ofW. The ?bound? water region seems to hold 3.5 water molecules (corresponding to 7 O−H oscillators) per AOT molecule and its
formation is nearly complete atW>6.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
10.
Stefan K. Kehrein Andreas Mielke Peter Neu 《Zeitschrift für Physik B Condensed Matter》1995,99(1):269-280
Using continuous unitary transformations recently introduced by Wegner [1], we obtain flow equations for the parameters of
the spin-boson Hamiltonian. Interactions not contained in the original Hamiltonian are generated by this unitary transformation.
Within an approximation that neglects additional interactions quadratic in the bath operators, we can close the flow equations.
Applying this formalism to the case of Ohmic dissipation at zero temperature, we calculate the renormalized tunneling frequency.
We find a transition from an untrapped to trapped state at the critical coupling constant α
c
=1. We also obtain the static susceptibility via the equilibrium spin correlation function. Our results are both consistent
with results known from the Kondo problem and those obtained from mode-coupling theories. Using this formalism at finite temperature,
we find a transition from coherent to incoherent tunneling atT
2
*
≈2T
1
*
, whereT
1
*
is the crossover temperature of the dynamics known from the NIBA. 相似文献
11.
F–B–S tri-doped titanium dioxide thin films on common glass were prepared by a modified sol–gel method, in which tetrabutyl
titanate (Ti(OC4H9)4) was chosen as the precursor and boric acid (H3BO3), sodium fluoride (NaF), and thiourea (N2H4CS) were employed as boron, fluorine, and sulfur sources, respectively. The microstructure and optical property were characterized
by X-ray diffraction, high-resolution field emission scanning electron microscopy, N2 adsorption–desorption isotherms, photoluminescence spectrum, and UV–Vis diffraction reflectance spectroscopy. The photocatalytic
performances were evaluated by decomposition of organic dyes in solution. The experimental results revealed that the F–B–S
tri-doped TiO2 thin film was composed of uniform round-like nano-particles with the size range of 5–8 nm. F–B–S tri-doping not only significantly promoted the UV-induced photodecomposition activities of TiO2 films but also extended the optical response of TiO2 red shift to visible light region, herein improving the visible light-induced degradation of organic dyes. The improvement
mechanism by F–B–S tri-doping was also discussed. 相似文献
12.
A. K. Patra P. U. Sastry Srirupa T. Mukherjee Vinila Bedekar A. K. Tyagi 《Pramana》2008,71(5):1057-1061
Ceria powders were prepared by gel combustion process using cerium nitrate and hitherto unexplored amino acids such as aspartic
acid, arginine and valine as fuels. The powders have been characterized by X-ray and laser diffraction. Cold pressed compacts
of these powders have been sintered at 1250°C for 2 h. Internal pore microstructure of the sintered compacts has been investigated
by small angle neutron scattering (SANS) over a scattering wave vector q range of 0.003–0.17 nm−1. The SANS profiles indicate surface fractal morphology of the pore space with fractal dimensionality lying between 2.70 and
2.76.
相似文献
13.
Different electroluminescence spectrums of the blueλ
max
=420 nm wide-banded low-temperature low-voltage radiation of CdF2-RE films at different levels of excitation in the region of temperatures of 77–300K are investigated. The kinetic characteristics
and temperature dependence of this radiation are explored. An effect of the resonance interaction of the centers of luminescence
of the wide-band and line radiation of the RE-centers is found. A model of the center of the wide-band radiation is suggested.
It is shown that the “blue” radiation is caused by recombination of the carriers.
Institute of Physics of Semiconductors of the National Academy of Sciences of Ukraine, Nauka Ave., 45, 252028, Kiev. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 127–132, January–February, 1999. 相似文献
14.
The total (p, n) reaction cross section for48Ca has been measured as a function of proton energy in the energy range 1.885 to 5.100 MeV with an overall resolution of ∼
2 keV and in ∼ 5 keV energy steps. The fluctutions in fine resolution data have been analysed to determine the average coherence
width 〈Γ〉. The excitation function averaged over large energy intervals has been analyzed in terms of the optical model. The
isobaric analogue resonances atE
p
∼ 1.95 and 4 MeV have been shape-analyzed to extract the proton partial width and the spectroscopic factorS
n
. A comparison of the gross structures observed in ∼ 55 keV averaged excitation function with the predictions of Izumo’s partial
equilibrium model has also been made. 相似文献
15.
G. M. Luke L. P. Le B. J. Sternlieb Y. J. Uemura J. H. Brewer R. Kadono R. F. Kiefl S. R. Kreitzman T. M. Riseman C. E. Stronach M. Davis S. Uchida H. Takagi Y. Tokura Y. Hidaka T. Murakami E. A. Early J. T. Markert M. B. Maple C. L. Seaman 《Hyperfine Interactions》1991,63(1-4):311-317
We report muon spin relaxation/rotation measurements on sintered powder samples of Nd2−x
Ce
x
CuO4−y
and a large single crystal of Nd2CuO4−y
. We find an electronic phase diagram which is quite similar to that of hole-doped superconductors such as La2−x
Sr
x
CuO4−y
, although the doping of electrons into the system is less efficient in destroying the static moments on the copper spins.
Static magnetic order in Nd2CuO4−y
appears below about 250 K, and two spin reorientations are seen atT=75 K andT=35 K. Measurements of the magnetic field penetration depth have been unsuccessful due to the rare-earth paramagnetism of
these materials. 相似文献
16.
In the paper the dependence of the photorefraction (PhR) in LiNbO3 and LiNbO3−Fe (0.1 wt%, 0.3wt%) crystals on light intensity (within 1016–1023 quanta·cm−2·s−1 at wavelengths 496.5 nm and 600 nm) and temperature (in the region 100–500 K) is studied. For all the crystals the limiting
values of PhR are similar and atT=293 K Δn
sat
lim
≈3·10−3. In LiNbO3 the temperature dependence of PhR in the range 100–500 K requires to take into account at least two trapping centres. 相似文献
17.
I. O. Bashkin M. V. Nefedova V. G. Tissen E. G. Ponyatovskii 《Physics of the Solid State》1998,40(12):1950-1952
The pressure dependence of the superconducting transition temperature in TiD0.74 has been measured up to 30 GPa in a diamond high-pressure chamber. It is found that the deuteride TiD0.74 becomes a superconductor at pressures corresponding to the transition to the high-pressure ζ phase, with a transition temperature that increases from 4.17 to 4.43 K in the interval P=14–30 GPa. The value extrapolated to atmospheric pressure T
c
(0)=4.0 K is significantly lower than the superconducting transition temperature (T
c
=5.0 K) measured earlier in the metastable state obtained by quenching TiD0.74 under pressure. It is assumed that the significant difference of the extrapolated value from the superconducting transition
temperature in the metastable state after quenching under pressure is caused by a phase transition on the path from the stability
region of the ζ phase under pressure to the region of the metastable state at atmospheric pressure.
Fiz. Tverd. Tela (St. Petersburg) 40, 2153–2155 (December 1998) 相似文献
18.
The pressure sensitive paint (PSP) intensity and lifetime system is an optical measurement technique to investigate absolute
pressure fields on model surfaces for basic research in laboratories, industrial wind tunnels or high speed rotating turbo
machines. Detailed qualitative and quantitative information and understanding of flow phenomena can be obtained in speed ranges
from U∞=20 m/s up to Ma=5.0. A number of projects of industrial interest has been investigated in different wind tunnels covering
low speed, transonic, trisonic and cryogenic facilities. The influence of the main error sources for the components of the
PSP system have been checked. Comparison of experimental pressure fields obtained by means of PSP and the results of numerical
calculations have been carried out. Different wind tunnel models ranging from basic configurations such as a cropped delta
wing to a complex half model of a large propeller-driven transport aircraft with all flaps, rudders and shrouds, and rotating
or oscillating models as well as Reynolds number effects on models have been investigated. 相似文献
19.
The glass transition in Ge
x
Se1−x
) (0·1 ⩽x ⩽ 0·25) glasses has been investigated using the photoacoustic (PA) technique. It is found that the PA amplitude and phase
undergo anomalous changes at the glass transition temperatureT
g. The amplitude has critical minimum and phase has maximum values atT
g. The variation of the thermal diffusivity, determined by measuring the frequency dependence of the PA amplitude and phase,
with temperature shows sharp decrease near the glass transition temperature. The temperature dependence of the optical energy
gap also has been measured and it shows a decrease with temperature for all compositions, the rate of decrease being higher
for temperatures greater thanT
g. 相似文献
20.
The electron spin resonance (ESR) spectra for each beige and brown sepiolites from Polatli-Ankara, Turkey, a clay mineral of Mg8Si12O30(OH)4(OH2)4(H2O)8, at 77 K have their own single characteristic peak atg ≈ 1.99, which begins to anneal from 437 and 536°C, respectively. The sextet lines of Mn2+ were also observed in addition to two peaks (g = 4.4 and 5.0) associated with Fe3+. A high-quality sepiolite called “meerschaum” from Sepetci-Eskisehir, Turkey, has two characteristic peaks atg ≈ 1.99, which begins to anneal from 419°C, and atg ≈ 2.03. ESR intensities of the signal atg ≈ 1.99 for beige, brown sepiolites and meerschaum are enhanced by γ-ray irradiation to give equivalent dosesD E = 11.8 ± 3.4, 4.7 ± 2.3 and 4.6 ± 1.2 kGy, respectively. The ESR ages obtained by assessing the annual dose rate from the content of238U,232Th and40K determined by γ-ray spectroscopy are 1.8 ± 0.8, 0.7 ± 0.5 and 0.9 ± 0.2 Ma, respectively, falling into the Pliocene Epoch in geological time scale in agreement with the stratigraphy. 相似文献