30 resultados para CR4
Resumo:
For the first time, to the best of our knowledge, a radially polarized laser pulse was produced from a passively Q-switched Nd:YAG ceramic microchip laser with a piece of Cr4+:YAG crystal as the saturable absorber and multilayer concentric subwavelength grating as the polarization-selective output coupler. The averaged laser power reached 450 mW with a slope efficiency of 30.2%. The laser pulse had a maximum peak power of 759 W, a minimum pulse duration of 86 ns, and a 6.7 kHz repetition rate at 3.7 W absorbed pump power. The polarization degree of the radially polarized pulse was measured to be as high as 97.4%. Such a radially polarized laser pulse with a high peak power and a short width is important to numerous applications such as metal cutting. (C) 2008 Optical Society of America
Resumo:
Infrared (1.2-1.6 mum) luminescence in a yttrium aluminium garnet (YAG) crystal, co-doped with Yb (10 at.%) and Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (lambda = 940 nm). The Cr4+ emission band was observed with its peak at 1.35 mum and measured to be about 6% with respect to Yb3+ IR luminescence (lambda = 1.03 mum). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+-Cr4+ energy transfer is a mechanism responsible for the B-3(2)(T-3(2))-B-3(1)((3)A(2)) emission of Cr4+ ions. This crystal is promising as an efficient source of the near infrared emission. (C) 2004 Elsevier B.V. All rights reserved.
Resumo:
The broadband emission in the 1.2 similar to 1.6 mu m region from Li2O-Al2O3-ZnO-SiO2 ( LAZS) glass codoped with 0.01mol.% Cr2O3 and 1.0mol.% Bi2O3 when pumped by the 808nm laser at room temperature is not initiated from Cr4+ ions, but from bismuth, which is remarkably different from the results reported by Batchelor et al. The broad similar to 1300nm emission from Bi2O3-containing LAZS glasses possesses a FWHM ( Full Width at Half Maximum) more than 250nm and a fluorescent lifetime longer than 500 mu s when excited by the 808nm laser. These glasses might have the potential applications in the broadly tunable lasers and the broadband fiber amplifiers. (c) 2005 Optical Society of America.
Resumo:
(Cr^4+Nd^3+GGG)QCrCr^4+GGGNd^3+GGG(Cr^4+Nd^3+)GGG(Cr^4+Nd^3+)GGGNd^3+GGG33s250s(Cr^4+Nd^3+)GGGQ
Resumo:
(Cr^4+Nd^3+:GGG)CrNdJuddofeltt(t=246)McCumber^4F3/2^4I11/2Cr^3+300900nmCr^3+Nd^3+Cr^4+106m
Resumo:
CrAl2O3Al2O3Cr^3Mg^2Cr^4Cr^41223nmCr^437nm
Resumo:
CXCR4 cDNA ,HIV-1 , RT- PCR ,,DNA 1059bp CXCR4 (tsCXCR4) cDNACXCR4 (hCXCR4) cDNA 9218 % , 9619 % hCXCR4 ,tsCXCR4 N 7 12 ,1415 32 ,183 ,188 , 193262 97 CX2 CR4 HIV-1
Resumo:
A passively Q-switched and mode-locked diode-pumped Nd:GdVO4 laser was demonstrated using a low-temperature-grown GaAs wafer (LT-GaAs) as an intracavity saturable absorber. The maximal Q-switched mode-locked average output power was 750 mW with the Q-switched envelop having a repetition rate of 167 kHz. The mode-locked pulse trains inside the Q-switched pulse envelope had a repetition rate of similar to 790 MHz.
Resumo:
We have demonstrated an efficient and compact passively Q-switched and mode-locked (QML) 1064 nm Nd:YVO4 laser by using a low temperature grown GaAs (LT-GaAs) saturable absorber as well as an output coupler. Stable QML with envelope duration as short as 10 ns and Q-switched repetition rate of 36 kHz was obtained. It is the shortest envelope duration as far as we know, and it is so short that it can be used as Q-switching pulses directly. At 6.9 W of the incident pump power, average output power of 1.24 W was achieved and the corresponding peak power and energy of a single Q-switched pulse were 3.44 kW and 34.4 mu J, respectively. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of 780 MHz. (C) 2005 Elsevier B.V. All rights reserved.
Resumo:
Simultaneous Q-switching and mode-locking (QML) is accomplished in a diode-pumped Nd:YAG laser using low-temperature GaAs (LT-GaAs) as the saturable absorber, which also acts as an output coupler at the same time. The repetition rate of the Q-switched envelope increased from 25 to 40 kHz as the pump power increased from 2.2 to 6.9 W. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of 714 MHz. A maximum average output power of 770 mW was obtained. (c) 2005 Elsevier GmbH. All rights reserved.
Resumo:
GGAGGA+UU Sr2FeMoO6Sr2CoMoO6Sr2FeMoO6Sr2CoMoO6Ba2YIrO6Ba2LaIrO6 Fm-3m, R-3 P21/nBa2YIrO6Ba2LaIrO6 P21/nR-3 Mn-O-MnYBaMn2O5Mn-O-Mn 157.8oG-A-170170AGYBaMn2O5GAYBaMn2O5 CaCu3M4O12 M3dTi, V, Cr, Mn, Fe, CoMMCaCu3Ti4O12Ti4+d0Cu-CuCaCu3M4O12 (M= V4+d1, Cr4+d2, Mn4+d3, Fe4+d4dn0<n<5)Cu-M Cu-CuM-MCaCu3Co4O12Co4+d5Cu-Cu, Cu-CoCo-CoMCaCu3Ti4O12Ti4+t2g0CaCu3V4O12V4+t2g1CaCu3Cr4O12Cr4+t2g2CaCu3Mn4O12Mn4+t2g3CaCu3Fe4O12Fe4+t2g3eg1CaCu3Co4O12Co4+t2g5 CaCu3Cr2Sb2O12CaCu3Cr4O12 Sb5+ Cr-CrCr3+3dCaCu3Cr2Sb2O12CaCu3Cr4O12 MSb5+MCaCu3Fe4O12CaCu3Co4O12CaCu3Fe2Sb2O12 CaCu3Ru4O12Ru4+4d4CaCu3Ru4O12Ru-O dpRu-O-RuRu 4dCu 3dO 2pCu 3dRu 4dCaCu3Ru4O12CaRuO3CaRuO3Ru-O-Ru
Resumo:
X,(SESAM),KerrCr4+YAG.80 fs,120 MHz,100 W.
Resumo:
Q,Cr4+:YAG,Cr:Forsterite.
Resumo:
The electronic and magnetic properties of CaCu3Cr4O12 and CaCu3Cr2Sb2O12 are investigated by the use of the full-potential linearized augumented plane wave (FPLAPW) method. The calculated results indicate that CaCu3- Cr4O12 is a ferrimagnetic and half-metallic compound, in good agreement with previous theoretical studies. CaCu3- Cr2Sb2O12 is a ferrimagnetic semiconductor with a small gap of 0.136 eV. In both compounds, because Cr4+ 3d (d(2)) and Cr3+ 3d (d(3)) orbitals are less than half filled, the coupling between Cr-Cu is antiferromagnetic, whereas that between Cu-Cu and Cr-Cr is ferromagnetic. The total net spin moment is 5.0 and 3.0 mu(B) for CaCu3Cr4O12 and CaCu3Cr2Sb2O12, respectively. In CaCu3Cr4O12, the 3d electrons of Cr4+ are delocalized, which strengthens the Cr-Cr ferromagnetic coupling. For CaCu3Cr2Sb2O12, the doping of nonmagnetic ion Sb5+ reduces the Cr-Cr ferromagnetic coupling, and the half-filled Cr3+ t(2g) (t(2g)(3)) makes the chromium 3d electrons localized. In addition, the ordering arrangement of the octahedral chromium and antimony ions also prevents the delocalization of electrons. Hence, CaCu3Cr2Sb2O12 shows insulating behavior, in agreement with the experimental observation.
Resumo:
The catalytic performance of silver-modified ZSM-5 catalysts in the selectively catalytic reduction (SCR) of NOx with methane was investigated. NO was selectively reduced by CH4 to N-2 in the presence of excess O-2, and the catalytic activity depended on both the activation of CH4 and the adsorption properties of NOx. Silver incorporated in ZSM-5 zeolite activated CH4 at low temperatures and lowered the "light-off" temperature for the CH4-SCR of NOx. Temperature-programmed (TP) spectroscopy studies depicted that surface nitrosyl species directly decomposed to N-2 in the absence of O-2. CH4 could not effectively reduce surface nitrosyl species, but might facilitate the direct decomposition of NO through the removal of surface oxygen. Surface nitrates were formed in NO and O-2 coexisting system and could be effectively reduced by CR4 to nitrogen. The priority of surface nitrates to O-2 in the reaction with CH4 clearly demonstrated that CH4 selectively and preferentially reduced the surface nitrate species to N-2 in the excess of oxygen. (C) 2002 Elsevier Science B.V. All rights reserved.
