共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Bryushinin V. Golubev Y. Kumzerov D. Kurdyukov I. Sokolov 《Applied physics. B, Lasers and optics》2009,95(3):489-495
We report an experimental investigation of the non-steady-state photoelectromotive force in nanostructured GaN within porous
glass and polypyrrole within chrysotile asbestos. The samples are illuminated by an oscillating interference pattern created
by two coherent light beams and the alternating current is detected as a response of the material. Dependences of the signal
amplitude versus temporal and spatial frequencies, light intensity, and temperature are studied for two wavelengths λ=442 and 532 nm. The conductivity of the GaN composite is measured: σ=(1.1–1.6)×10−10 Ω−1 cm−1 (λ=442 nm, I
0=0.045–0.19 W/cm2, T=293 K) and σ=(3.5–4.6)×10−10 Ω−1 cm−1 (λ=532 nm, I
0=2.3 W/cm2, T=249–388 K). The diffusion length of photocarriers in polypyrrole nanowires is also estimated: L
D=0.18 μm. 相似文献
2.
V. A. Andronov S. A. Bel’kov A. V. Bessarab I. N. Voronich S. G. Garanin A. A. Gorbunov V. N. Derkach G. V. Dolgoleva A. I. Zaretskii V. M. Izgorodin B. N. Ilyushechkin G. A. Kirillov G. G. Kochemasov Yu. V. Kuratov V. I. Lazarchuk V. A. Lebedev V. M. Murugov L. S. Mkhitar’yan A. V. Okutin S. I. Petrov A. V. Pinegin N. N. Rukavishnikov A. N. Razin A. V. Ryadov A. V. Senik N. A. Suslov S. A. Sukharev V. A. Tokarev 《Journal of Experimental and Theoretical Physics》1997,84(3):485-488
The results of the first experiments devised to investigate the mixing of thin layers of Al and Au during the laser acceleration
of flat three-layer targets of Si (5 μm), Al (2 μm), and Au (0.05–0.26 μm) by radiation converted to the second harmonic from the Iskra-4 iodine laser with an intensity of 4×1013−7×1013 W/cm2 (τ
0.5∼1 ns), which acts on the Si side of the target. A method for detecting the occurrence of mixing is developed. It is established
that under the experimental conditions the thickness of the mixing region is at least ∼0.15 μm. The results of a theoretical analysis of the evolution of the disturbances leading to mixing are presented.
Zh. éksp. Teor. Fiz. 111, 882–888 (March 1997)
Deceased. 相似文献
3.
F. Gueye E. Safari M. Chenevier G. Guelachvili N. Picqué 《Applied physics. B, Lasers and optics》2005,81(8):1143-1147
A high-resolution time-resolved Fourier transform interferometer is combined with a multimode Cr4+:YAG laser for intracavity laser absorption spectroscopy (ICLAS) experiments. Atmospheric absorption spectra are recorded
in the 1.5 μm region with a minimum detectable absorption coefficient equal to 8×10-11 cm-1 Hz-1/2. The broad gain bandwidth of the crystal allows a simultaneous spectral coverage at most equal to 38 nm. The laser tunability
covers the 1360–1577 nm range. Water vapor detection domain extends from the 100 ppmv down to the 0.1 ppbv level.
PACS 42.62.Fi; 39.30.+w; 07.60.Ly; 33.20.Ea 相似文献
4.
V. M. Gordienko I. A. Makarov V. P. Petukhov A. S. Khomenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(2):183-188
The dependence of the characteristic X-ray radiation yield from CaF2 crystal on the formed microchannel depth under highly intensive (I ∼ 3 × 1015 W/cm2) laser pulses with different contrast was obtained. The maximum of the characteristic X-ray radiation yield at these experimental
conditions corresponded to the microchannel depth of 30–50 μm. The efficiency of the laser radiation conversion to the characteristic
X-ray radiation increased from 6 × 10−8 for the surface up to 10−7 in the microchannel. The dependence of the characteristic X-ray radiation yield on the viewing angle showed that the source
of X-ray radiation was located near the surface inside the microchannel. 相似文献
5.
We describe a new technique to measure the UV/visible absorption spectrum of the ablated material during the laser pulse.
The technique utilizes the continuum emission from one laser produced plasma as a light source to measure the absorption properties
of a second laser produced plasma which is formed on a semi-transparent target with an array of 40 μm holes. A 6 ns, 1064
nm laser was used to ablate a Ag target and the plasma absorption was measured in the range 450–625 nm for a laser fluence
of 1 J cm−2. The total absorption cross-section is (0.5–1.5)×10−17 cm2 in the range 450–540 nm. By comparing the measured absorption with a calculation using the plasma spectroscopy code FLYCHK
it can be concluded that, in the wavelength region examined here, the absorption is mainly due to bound-bound transitions. 相似文献
6.
Enhanced field emission from pulsed laser deposited nanocrystalline ZnO thin films on Re and W 总被引:1,自引:0,他引:1
Dattatray J. Late Pankaj Misra B. N. Singh Lalit M. Kukreja Dilip S. Joag Mahendra A. More 《Applied Physics A: Materials Science & Processing》2009,95(2):613-620
Nanocrystalline ZnO thin films have been deposited on rhenium and tungsten pointed and flat substrates by pulsed laser deposition
method. An emission current of 1 nA with an onset voltage of 120 V was observed repeatedly and maximum current density ∼1.3 A/cm2 and 9.3 mA/cm2 has been drawn from ZnO/Re and ZnO/W pointed emitters at an applied voltage of 12.8 and 14 kV, respectively. In case of planar
emitters (ZnO deposited on flat substrates), the onset field required to draw 1 nA emission current is observed to be 0.87
and 1.2 V/μm for ZnO/Re and ZnO/W planar emitters, respectively. The Fowler–Nordheim plots of both the emitters show nonlinear
behaviour, typical for a semiconducting field emitter. The field enhancement factor β is estimated to be ∼2.15×105 cm−1 and 2.16×105 cm−1 for pointed and 3.2×104 and 1.74×104 for planar ZnO/Re and ZnO/W emitters, respectively. The high value of β factor suggests that the emission is from the nanometric features of the emitter surface. The emission current–time plots
exhibit good stability of emission current over a period of more than three hours. The post field emission surface morphology
studies show no significant deterioration of the emitter surface indicating that the ZnO thin film has a very strong adherence
to both the substrates and exhibits a remarkable structural stability against high-field-induced mechanical stresses and ion
bombardment. The results reveal that PLD offers unprecedented advantages in fabricating the ZnO field emitters for practical
applications in field-emission-based electron sources. 相似文献
7.
The spatial characteristic of an aluminum laser-induced plasma are studied at a laser radiation intensity of (3.8–4.8) × 108 W/cm2 and an air residual pressure of 6.7–133.3 Pa. It is found that the duration of the aluminum plasma glow is 50 μs and decreases
with decreasing laser power output. The glow intensity reaches a maximum at t = 1.4 μs and rises with laser energy. Typical sizes of the emitting area on the laser torch are determined. 相似文献
8.
A. M. Efimov A. I. Ignat’ev N. V. Nikonorov E. S. Postnikov 《Optics and Spectroscopy》2011,111(3):426-433
We have measured the UV absorption spectra of photothermorefractive glasses of the system Na2O-ZnO-Al2O3-NaF-SiO2 doped by cerium oxide in the range of (2.8–5.0) × 104 cm−1 (360–200 nm). The spectra have been processed by the method of dispersion analysis based on the analytical convolution model
for the complex dielectric function of glasses. We show that the absorption band centered at 3.3 × 104 cm−1 (∼303 nm) that is attributed to the transition 2F
5/2 → 5d in the Ce3+ ion, is an envelope of three spectral components. The broad absorption range (3.5–4.7) × 104 cm−1 (200–270 nm) that is commonly interpreted as a charge transfer band of the Ce(IV) valence state, is an envelope of at least
three spectral components. 相似文献
9.
A sequential three-dimensional (3D) particle-in-cell simulation code PICPSI-3D with a user friendly graphical user interface
(GUI) has been developed and used to study the interaction of plasma with ultrahigh intensity laser radiation. A case study
of laser–plasma-based electron acceleration has been carried out to assess the performance of this code. Simulations have
been performed for a Gaussian laser beam of peak intensity 5 × 1019 W/cm2 propagating through an underdense plasma of uniform density 1 × 1019 cm − 3, and for a Gaussian laser beam of peak intensity 1.5 × 1019 W/cm2 propagating through an underdense plasma of uniform density 3.5 × 1019 cm − 3. The electron energy spectrum has been evaluated at different time-steps during the propagation of the laser beam. When the
plasma density is 1 × 1019 cm − 3, simulations show that the electron energy spectrum forms a monoenergetic peak at ~14 MeV, with an energy spread of ±7 MeV.
On the other hand, when the plasma density is 3.5 × 1019 cm − 3, simulations show that the electron energy spectrum forms a monoenergetic peak at ~23 MeV, with an energy spread of ±7.5 MeV. 相似文献
10.
A. N. Vystavkin D. V. Shuvaev L. S. Kuz’min M. A. Tarasov E. Aderstedt M. Willander T. Claeson 《Journal of Experimental and Theoretical Physics》1999,88(3):598-602
This paper describes the design and experimental testing of a high-sensitivity hot-electron bolometer based a film of normal
metal, exploiting the Andreev reflection from superconductor boundaries, and cooled with the help of a superconductor-insulator-normal
metal junction. At the measured thermal conductivity, G≈6×10−12 W/K, and a time constant of τ=0.2 μs, and a temperature of 300 mK, the estimated noise-equivalent power NEP=5×10−18 W/Hz1/2, assuming that temperature fluctuations are the major source of noise. At a temperature of 100 mK, the thermal conductivity
drops to G≈7×10−14 W/K, which yields NEP=2×10−19 W/Hz1/2 at a time constant of τ=5 μs. The microbolometer has been designed to serve as a detector of millimeter and FIR waves in space-based radio telescopes.
Zh. éksp. Teor. Fiz. 115, 1085–1092 (March 1999) 相似文献
11.
M. L. Hamilton R. Peverall G. A. D. Ritchie L. J. Thornton J. H. van Helden 《Applied physics. B, Lasers and optics》2009,97(3):715-722
We have demonstrated the production of ∼1.9 μm near-infrared radiation by using difference frequency generation within a 5%
MgO doped PPLN crystal by coupling ∼735 nm radiation from a tunable external cavity diode laser with relatively high powered
532 nm radiation from both Nd:YVO3 and Nd:YAG lasers. The radiation produced is of low power, ∼15 μW, and was used in conjunction with the sensitivity enhancing
techniques of wavelength modulation spectroscopy (WMS) and cavity enhanced absorption spectroscopy (CEAS). Experiments were
carried out on rotationally resolved transitions in the combination bands of NH3 and CO2 in the 1.9 μm region. An α
min value of 3.6×10−6 cm−1 Hz−1/2 was achieved for WMS measurements on CO2. A comparable α
min value of 2.2×10−6 cm−1 Hz−1/2 was achieved for NH3 using CEAS. The low NIR power indicates that despite the level of MgO doping quoted for the crystal, under prolonged exposure
photorefractive damage has occurred. 相似文献
12.
Lee Ming-Kwei Yen Chih-Feng Chiu Shih-Chen 《Applied Physics A: Materials Science & Processing》2011,104(4):1175-1180
The electrical characteristics of thin TiO2 films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO2 film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10−2 and 1.1×10−4 A/cm2 at +2 V bias and 1.6×10−1 and 8.3×10−4 A/cm2 at −2 V bias. The lower leakage currents of TiO2 with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide
charge number density are 33 and 2.5×1013 cm2, respectively. The lowest mid-gap interface state density is around 7.6×1011 cm−2 eV−1. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range
of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm. 相似文献
13.
J. P. Xu X. Zou C. X. Li P. T. Lai C. L. Chan 《Applied Physics A: Materials Science & Processing》2009,94(2):419-422
Reactive cosputtering is employed to prepare high-permittivity HfTiO gate dielectric on n-Ge substrate. Effects of Ge-surface
pretreatment on the interface and gate leakage properties of the dielectric are investigated. Excellent performances of Al/HfTiO/GeO
x
N
y
/n-Ge MOS capacitor with wet–NO surface pretreatment have been achieved with a interface-state density of 2.1×1011 eV−1 cm−2, equivalent oxide charge of −7.67×1011 cm−2 and gate leakage current density of 4.97×10−5 A/cm2 at V
g
=1 V. 相似文献
14.
We report here an experimental study of the ionic keV X-ray line emission from magnesium plasma produced by laser pulses of
three widely different pulse durations (FWHM) of 45 fs, 25 ps and 3 ns, at a constant laser fluence of ∼1.5 × 104 J cm − 2. It is observed that the X-ray yield of the resonance lines from the higher ionization states such as H- and He-like ions
decreases on decreasing the laser pulse duration, even though the peak laser intensities of 3.5 × 1017 W cm − 2 for the 45 fs pulses and 6.2 × 1014 W cm − 2 for the 25 ps pulses are much higher than 5 × 1012 W cm − 2 for the 3 ns laser pulse. The results were explained in terms of the ionization equilibrium time for different ionization
states in the heated plasma. The study can be useful to make optimum choice of the laser pulse duration to produce short pulse
intense X-ray line emission from the plasma and to get the knowledge of the degree of ionization in the plasma. 相似文献
15.
A nanoparticle TiO2 solid-state photoelectrochemical cell utilizing as a solid electrolyte of poly(acrylonitrile)–propylene–carbonate–lithium
perchlorate (PAN–PC–LiClO4) has been fabricated. The performance of the device has been tested in the dark and under illumination of 100-mW cm−2 light. A nanoparticle TiO2 film was deposited onto indium tin oxide-covered glass substrate by controlled hydrolysis technique assisted with spin-coating
technique. The average grain size for the TiO2 film is 76 nm. LiClO4 salt was used as a redox couple. The room temperature conductivity of the electrolyte is 4.2 × 10−4 S cm−1. A graphite electrode was prepared onto a glass slide by electron beam evaporation technique. The device shows the rectification
property in the dark and shows the photovoltaic effect under illumination. The best J
sc and V
oc of the device were 2.82 μA cm−2 and V
oc of 0.58 V, respectively, obtained at the conductivity of 4.2 × 10−4 S cm−1 and intensity of 100 mW cm−2. The J
sc was improved by about three times by introducing nanoparticle TiO2 and by using a solid electrolyte of PAN–PC–LiClO4 replacing PVC–PC–LiClO4 in the device. The current transport mechanism of the cell is also presented in this paper. 相似文献
16.
Zhao C. C. He M. Z. Hang Y. Yin J. G. Zhang L. H. He X. M. Gong J. Yu T. Chen W. B. 《Laser Physics》2012,22(5):918-921
Polarized absorption and fluorescence spectra Nd3+-doped LiLuF4 single crystal were investigated. The peak emission cross section at 905 and 910 nm are 0.97 × 10−20 and 0.82 × 10−20 cm2, respectively. Two samples with different dimensions were tested in the laser experiments. With a laser-diode as the pump
source, a maximum 1.17 W laser output at 910 nm has been obtained with a slope efficiency of 16.3% with respect to the pump
power. 相似文献
17.
We report an efficient operation of a kilohertz nanosecond extracavity KGd(WO4)2 (KGW) crystal Raman yellow laser, which is pumped by a 532 nm lasers based on pulse laser diode (LD) side-pumped ceramic
Nd: YAG, BBO electro-optical Q-switched and LBO crystal extracavity frequency doubling. With the 5 W, 10 ns and 1 kHz output
power pumped at 532 nm, we obtained 2.58 W, 7.4 ns, 1 kHz second Stokes Raman laser output at 579.54 nm for 768 cm−1 Raman shift of KGW crystal, corresponding to a conversion efficiency of 51.4%. By changing the KGW crystal orientation, we
further obtained 3.18 W, 7.8 ns, 1 kHz Raman pulses at 588.33 nm for 901 cm−1 Raman shift, corresponding to a conversion efficiency of 63.3%. The beam quality factors M2 of 579.54 and 588.33 nm were (M
x−579.542 = 5.829, M
y−579.542 = 6.336) and (M
x−588.332 = 6.405, M
y−588.332 = 6.895), respectively. 相似文献
18.
Experimental performance parameters of Hg implanted Hg1−x
Cd
x
Te photovoltaic detectors are analyzed. At 77K, for 8–14 μm band, a comparison is made between performances and theoretical
ultimate diffusion limits in low frequency direct detection. Experimental features are well-explained by a model based on
the Auger band-to-band process for carrier recombination. Peak detectivities exceeding 1011 cm Hz1/2W−1, external quantum efficiencies as high as 90%, and zero-bias resistance-area products better than 1 Ω·cm2 have been achieved in devices with 12 μm cutoff wavelengths. In the 3–5 μm band performances are far from the diffusion limit.
Notwithstanding, at 77K zero-bias resistance-area products are better than 104Ω·cm2 and detectivities of the order of 1012 cm Hz1/2W−1 were observed at 5 μm.
Predominant generation-recombination contribution are present at room temperature in 1–1.3 μm photodiodes whose detectivities,
primarily limited by the Johnson noise, at 1.3 μm are higher than 1011 cm Hz1/2W−1 at 300 K.
The high frequency response of the photodiodes is also discussed. Response times as low as 0.5 ns are reached despite some
limitations arising from the implanted layer sheet resistance.
Work supported by CNR-CISE contract No. 73.01435. 相似文献
19.
The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd3+ ions in CaNb2O6 crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10−20 cm2 with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd3+ ions in CaNb2O6 crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω
t
are Ω
2=5.321×10−20 cm2,Ω
4=1.734×10−20 cm2,Ω
6=2.889×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β
1=36.03%,β
2=52.29%,β
3=11.15%,β
4=0.533%. The emission cross section at 1062 nm is 9.87×10−20 cm2. 相似文献
20.
The luminescence kinetics of the Cd II ion at a wavelength of 441.6 nm has been studied experi-mentally in a high-pressure
He-Cd mixture in the presence of Ar, Ne, Xe, and CCl4 impurities. Cadmium ions were excited through the bombardment of a cadmium foil heated up to 240°C by a pulsed electron beam
with an electron energy of 150 keV, a pulse duration of 3 ns, and a current of 500 A. The constants of collisional quenching
of the Cd II 5s
2
2
D
5/2 level by Ar, Ne, and Xe atoms and CCl4 molecules and the integral luminescence quenching constants of this level in the helium medium by these impurity gases have
been determined. The constants of collisional quenching appeared to be 8.1 × 10−12 (Ar), 1.2 × 10−12 (Xe), 1.5 × 10−13 (Ne), and 1.8 × 10−10 cm3/s (CCl4, for λ = 325 nm), while the integral constants were found to be, respectively, 4.1 × 10−11, 3.4 × 10−11, 9.5 × 10−12, 1.4 × 10−9 cm3/s for Ar, Ne, Xe, and CCl4 at a buffer gas pressure of 1 atm.
Original Russian Text ? A.I. Miskevich, Liu Tao, 2009, published in Optika i Spektroskopiya, 2009, Vol. 107, No. 1, pp. 45–49. 相似文献