排序方式: 共有26条查询结果,搜索用时 296 毫秒
11.
J. V. Alvarez-Bravo N. Bolognini L. Arizmendi 《Applied physics. B, Lasers and optics》1996,62(2):159-164
Changes in the angular Bragg selectivity of volume holograms stored in photorefractive LiNbO3 are analysed for different experimental conditions in the transmission geometry. The effects of the refractive-index-change amplitude, the grating period, the modulation depth, and the wave-front modulation of the signal beam are considered. A very good agreement of the results with the off-Bragg diffraction theory is observed. 相似文献
12.
C. M. Arizmendi L. N. Epele H. Fanchiotti C. A. García Canal 《Zeitschrift für Physik B Condensed Matter》1986,64(2):231-235
A renormalization group realization, allowing the simultaneous and analytic study of both the ferromagnetic and antiferromagnetic phases of the Blume-Capel model, is applied in (1+1)_and (2+1) dimensions. The model is also analyzed by using a variational technique. Critical and tricritical parameters are determined and the phase diagram is exhibited.Partially supported by CONICET, CIC Pcia. de Buenos Aires and SUBCYT, Argentina 相似文献
13.
Lifetimes of thermally fixed holograms in LiNbO(3):Fe crystals 总被引:1,自引:0,他引:1
The thermal erasure decay at different temperatures of holographic gratings thermally fixed in iron-doped lithium niobate has been exhaustively studied. An activation energy of 0.94 eV was found to be independent of the grating fringe spacing. At a given temperature the decay time is strongly dependent on the grating spacing. This dependence is well fitted to a square fringe spacing law, as predicted theoretically. From the experimental data the room-temperature hologram lifetime under illumination is extrapolated, giving as a result t(years)=(5.2+/-0.2)?(2) , with the grating spacing ? in micrometers. 相似文献
14.
Degaudenzi ME Arizmendi CM 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):6569-6573
The most abundant biological particles in the atmosphere are pollen grains and spores. Self-protection of a pollen allergy is possible through information about future pollen contents in the air. In spite of the importance of airborne pollen concentration forecasting, it has not been possible to predict the pollen concentrations with great accuracy, and about 25% of daily pollen forecasts result in failures. Previous analyses of the dynamic characteristics of atmospheric pollen time series indicate that the system can be described by a low dimensional chaotic map. We apply a wavelet transform to study the multifractal characteristics of an airborne pollen time series. The information and the correlation dimensions correspond to a chaotic system showing a loss of information with time evolution. 相似文献
15.
Off-congruent lithium niobate single crystals were grown by the Czochralski method with K2O added to the congruent melts in a concentration varying between 2 and 10.5 wt%. The Li/Nb ratio was determined by means of indirect methods such as the fundamental absorption edge positon, the IR vibrational spectrum, lattice parameters and the variation of the refractive indices. The data presented in this work show that the Li/Nb ratio can be controlled by the amount of K2O added to the congruent melt. Moreover, the techniques employed for characterization are good tools for the determination of the Li/Nb ratio. 相似文献
16.
L. Arizmendi V. De Andrés E. M. De Miguel-Sanz M. Carrascosa 《Applied physics. B, Lasers and optics》2005,80(3):351-354
In this paper the thermal fixing of holographic gratings with K-vectors perpendicular to the crystallographic c-axis of LiNbO3 is considered in order to obtain information about anisotropy of the proton thermal diffusion in this crystal. Specifically, thermal decays of fixed holograms in particular crystallographic directions are measured and related with proton diffusion. The values obtained are compared with previous data of decays of fixed holograms with K-vector parallel to the c-axis. The results show a high anisotropy of the thermal diffusion of protons in lithium niobate crystals. 相似文献
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18.
L. Arizmendi C. de las Heras F. Jaque A. Suchocki S. Kobyakov T.P.J. Han 《Applied physics. B, Lasers and optics》2007,87(1):123-127
Polymer stabilized cholesteric texture cells with various chiral and monomer concentrations were fabricated. Electro-optical measurement indicates that the chiral concentration and the monomer concentration significantly influence the hysteresis, threshold voltage and field-on and field-off response times of the cell. The chiral dopant is found to increase the hysteresis width and to decrease the field-off response time of the cell. The monomer is found to decrease the hysteresis width and to increase the field-off response time of the cell. The field-on response time is independent of the monomer concentration and the chiral concentration of the cell. A thinner cell has a smaller hysteresis width. PACS 61.30.-v; 42.70.Df; 42.79.Kr 相似文献
19.
The effects of quenched disorder on the overdamped motion of a driven particle on a periodic, asymmetric potential are studied. While for the unperturbed potential the transport is due to a regular drift, the quenched disorder induces a significant additional chaotic "diffusive" motion. Possible applications to experiments in nanoscale surfaces and particle separation are discussed. 相似文献
20.
Cruz-Silva R Arizmendi L Del-Angel M Romero-Garcia J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(1):8-12
Polyaniline colloids were prepared by enzymatic polymerization using chitosan and poly(N-isopropylacrylamide) as steric stabilizers. The resulting nanoparticles undergo flocculation by changing the pH or temperature of the aqueous dispersions. The environmentally responsive behavior of these colloids contrasts with that of polyaniline colloids synthesized using poly(vinyl alcohol) as the steric stabilizer. The colloid size was a function of the steric stabilizers and ranged from approximately 50 nm for polyaniline particles prepared in the presence of chitosan and partially hydrolyzed poly(vinyl alcohol) up to 350 nm for the particles synthesized using poly(N-isopropylacrylamide). UV-visible and Fourier transform infrared spectroscopic studies indicate that polyaniline colloids are spectroscopically similar to those obtained by traditional dispersion polymerization of aniline by chemical oxidation. These polyaniline colloids have potential applications in thermochromic windows and smart fluids. 相似文献