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991.
992.
The temporal characteristics of stimulated Raman scattering (SRS) under 22-ps laser excitation were studied in eight oxide crystals with a T 2 optical-phonon dephasing time variable by up to two orders of magnitude. The measured SRS pulse width was shortened from 13.8 ps for Ba(NO3)2 (T 2 = 26.5 ps) to 4 ps for the LiNbO3 (T 2 = 0.38 ps) crystal. The dependence of SRS pulse width on the dephasing time was analyzed in the framework of the known SRS theory. 相似文献
993.
We have studied the characteristic features of carbazole phosphorescence quenching by benzophenone in toluene at 77 K. We
have shown that the decrease in the relative phosphorescence intensity for carbazole (energy donor) by a greater factor than
we see for the relative change in its decay time is due to the fact that a change in the phosphorescence decay time occurs
only for carbazole molecules participating in triplet-triplet energy transfer, while the substantial decrease in the phosphorescence
intensity for carbazole with no change in the phosphorescence decay time is connected with quenching of its singlet states.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 554–556, July–August, 2006. 相似文献
994.
Sergey A. Ponomarenko 《Optics Communications》2006,261(1):1-4
We describe a class of spatio-temporal optical pulses that spread neither spatially nor temporarily in linear dispersive media over long propagation distances. These new spatio-temporal pulses, referred to as linear optical bullets, can have any spatio-temporal profile and temporal width, and they carry a finite amount of energy. We also discuss in detail a technique for the experimental realization of linear optical bullets. 相似文献
995.
I. A. Khovanskaya 《Proceedings of the Steklov Institute of Mathematics》2006,254(1):201-230
The following weak infinitestimal Hilbert’s 16th problem is solved. Given a real polynomial H in two variables, denote by M(H, m) the maximal number possessing the following property: for any generic set {γ i } of at most M(H,m) compact connected components of the level lines H = c i of the polynomial H, there exists a form θ = P dx + Q dy with polynomials P and Q of degrees no greater than m such that the integral ∫ H=c θ has nonmultiple zeros on the connected components {γ i }. An upper bound for the number M(H,m) in terms of the degree n of the polynomial H is found; this estimate is sharp for almost every polynomial H of degree n. A multidimensional version of this result is proved. The relation between the weak infinitesimal Hilbert’s 16th problem and the following question is discussed: How many limit cycles can a polynomial vector field of degree n have if it is close to a Hamiltonian vector field? 相似文献
996.
B. I. Suleimanov 《Journal of Experimental and Theoretical Physics》2002,95(5):944-956
Solutions of the equations v x+v 3?tv+x=0 and v xx=v 3? tv+x, which describe the nucleation of domain walls occurring in the neighborhood of cusps of slowly varying equilibriums, are analyzed. Examples related to the diffusion in smoothly inhomogeneous media are considered. 相似文献
997.
998.
999.
M. Piana M. Arrabito S. Bodoardo A. D'Epifanio D. Satolli F. Croce B. Scrosati 《Ionics》2002,8(1-2):17-26
Solid State Reaction was employed to prepare phospho-olivines LiMPO4 (where M=Fe, Co) as pure phase and LiNiPO4 in presence of foreign phases, as cathodic materials for lithiumions batteries. The relationship between structural, morphological
and electrochemical properties were investigated in the case of LiFePO4. Structural investigation has been carried out by means of X-ray powder diffraction (XRPD) and Rietveld refinement. The influence
on the morphology of annealing temperature, different flowing gas mixture and addition of ascorbic acid during the synthesis,
has been analysed via scanning electron microscopy. The electrochemical cycling performances on LiFePO4 showed to be positively affected by the modifications of the experimental conditions. Cyclic voltammetry showed a good reversibility
during insertion-extraction mechanism, in particular in presence of additives. LiCoPO4 and LiNiPO4 are interesting as high voltage cathode materials for Li-ion batteries and have been taken into account, but their electrochemical
operating conditions are still to be optimised. In the case of LiNiPO4 it is very difficult to obtain, by solid state synthesis, suitable purity powders, having a grain size small enough to exploit
it usefully as cathodic material for Li-ion cells.
Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2000. 相似文献
1000.
V. A. Gundienkov S. I. Yakovlenko 《Journal of Experimental and Theoretical Physics》2002,95(5):864-877
The solution of the Poisson-Boltzmann equation for a cloud of charges surrounding two charged dust particles treated as Debye atoms forming a Debye molecule is investigated numerically using Cassini coordinates. The electric force exerted on a dust particle by the other dust particle was determined by integrating the electrostatic pressure on the surface of the dust particle. It is shown that attractive forces appear when the following two conditions are satisfied. First, the Debye radius (corresponding to the electron density at half the mean distance between the dust particles) must be approximately equal to half the mean distance between the dust particles. Attraction between the dust particles emerges at a distance equal approximately to half the mean distance between the dust particles. Second, attraction takes place when like charges are concentrated predominantly on the dust particles. If the particles carry a small fraction of charge of the same polarity, repulsion between the particles takes place at all distances. 相似文献