排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
G.M. Bilmes D.J.O. Orzi O.E. Martínez A. Lencina 《Applied physics. B, Lasers and optics》2006,82(4):643-648
The measurement of surface cleanliness is a significant problem in many industrial and technological processes. Existing methods are based on laboratory procedures, that are not performed in real time, can not be automated, and usually are restricted to a small portion of the sample. In this study we describe a new method for real time measurement of the amount of surface dirt or contamination deposited on a surface. It relies on the ablation of the surface dirt film by means of a short laser pulse, and the subsequent measurement of the emitted sound. The intensity of the sound is proportional to the amount of surface dirt and provides a direct measurement of the cleanliness of the surface. We also developed a reference sample for calibration, based on a uniform distribution of dots printed on white paper. The density and the dot size can be easily modified providing a homogeneous, uniform and reproducible standard for the measurement. Based on this method, we designed, developed and patented the first industrial instrument for on-line determination of the degree of cleanliness of manufactured cold rolled steel plate bobbins. PACS 79.20.D; 81.70.C; 42.62. 相似文献
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Perullini Mercedes Jobbágy Matías Bilmes Sara A. Torriani Iris L. Candal Roberto 《Journal of Sol-Gel Science and Technology》2011,59(1):174-180
Silica matrices synthesized from a pre-hydrolysis step in ethanol followed by alcohol removal at low pressure distillation,
and condensation in water, are suitable for encapsulation of biomolecules and microorganisms and building bioactive materials
with optimized optical properties. Here we analyze the microstructure of these hydrogels from the dependence of I(q) data acquired from SAXS experiments over a wide range of silica concentration and pH employed in the condensation step. From
the resulting data it is shown that there is a clear correlation between the microscopic parameters—cluster fractal dimension
(D), elementary particle radius (a) and cluster gyration radius (R)—with the attenuation of visible light when the condensation step proceeds at pH < 6. At higher pHs, there is a steep dependence
of the cluster density (~R
D−3) with the condensation pH, and non-monotonous changes of attenuance are less than 20%, revealing the complexity of the system.
These results, which were obtained for a wide pH and silica concentration range, reinforce the idea that the behavior of gels
determined in a restricted interval of synthesis variables cannot be extrapolated, and comparison of gelation times is not
enough for predicting their properties. 相似文献
4.
Ropero-Vega J. L. Candal Roberto J. Pedraza-Avella J. A. Niño-Gómez M. E. Bilmes Sara A. 《Journal of Solid State Electrochemistry》2019,23(6):1757-1765
Journal of Solid State Electrochemistry - Semiconductor heterojunction of β-Bi2O3-TiO2/ITO thin films was prepared by aqueous sol-gel and their photoelectrochemical and photoelectrocatalytic... 相似文献
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M. Villagrán-Muniz C. Garcia-Segundo H. F. Ranea-Sandoval C. Gogorza G. M. Bilmes 《Applied physics. B, Lasers and optics》1995,61(4):361-366
Stimulated emission in pulsed dye lasers was characterized in several experimental conditions by analyzing the changes in the acoustic signals generated in a dye solution, with the dye laser cavity either active or inhibited (i.e., by blocking the optical path or misaligning of the optical components). Pump energy threshold, optimum dye concentration, tuning range and maximum-emission wavelength of a rhodamine 6G dye laser were measured by this method. An approximate model for the photoacoustic signal generation consistent with the experiments is presented.Member of CONICET 相似文献
6.
J.O. Tocho G.M. Bilmes H.F. Ranea Sandoval 《Applied physics. B, Lasers and optics》1999,69(5-6):473-476
Second-harmonic conversion of the 532-nm pulsed output of a doubled Nd:YAG laser in KDP was characterized by analyzing the
changes in the acoustic signals generated in the crystal at different orientation conditions and for several incident fluences.
Using a piezoelectric transducer, phase-matching condition was determined by maximizing the amplitude of the acoustic signals
detected. The angular orientation for optimum harmonic efficiency was obtained with the same precision compared with the conventional
optical procedure. The origin of the photoacoustic signals is the relaxed energy following the absorption of 266-nm photons.
To determine the mechanisms of the 266-nm absorption processes, we also performed experiments under direct illumination with
the 266-nm emission of the quadrupled Nd:YAG laser. A combination of a linear and nonlinear process occurs. Direct absorption
by KDP as well as the participation of transient defects produced in the material were analyzed.
Received: 27 July 1998 / Revised version: 19 March 1999 / Published online: 19 August 1999 相似文献
7.
Daniel H. Murgida Gabriel M. Bilmes Rosa Erra-Balsells 《Photochemistry and photobiology》1996,64(5):777-784
Abstract— The photophysics of purinic compounds (purine, 6-meth-ylpurine, 6-aminopurine [adenine], 6-chloropurine, 6-methoxypurine) and theophylline in acetonitrile solution were studied by pulsed laser-induced optoacoustic spectroscopy (LIOAS) exciting at 266 nm. The effect of O2 , Xe and MnCl2 on the photophysical behavior of these compounds was studied; as well, the formation quantum yield of purine and 6-methylpurine triplet states were determined, with φT = 0.88 ± 0.03 for both compounds. Multiphotonic and depletion processes were observed at high laser fluences. In order to explain this behavior, theoretical UV-visible absorption electronic spectra from both the S0 and S1 state have been calculated for purines and theophylline by using the semiempirical PM3 and ZINDO/S methods. 相似文献
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Gervasi C. A. Méndez C. M. Bolzán A. E. Bilmes P. D. Llorente C. L. 《Journal of Solid State Electrochemistry》2016,20(4):1065-1074
Journal of Solid State Electrochemistry - Mott–Schottky analysis and electrochemical and X-ray photoelectron spectroscopy (XPS) measurements were performed on passive films formed on low-C... 相似文献
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Nora François Berta Ginzberg Sara A. Bilmes 《Journal of Sol-Gel Science and Technology》1998,13(1-3):341-346
Titania nanoparticles and gels are synthesized in reverse micelles with either an ionic (AOT) or a non-ionic (Triton X-100) surfactant in alkanes with low water contents. Acids were in some cases dissolved in the aqueous phase. Whereas the size of the sol nanoparticles is independent of the micellar composition, the kinetics of the sol-gel transition are not. The gelation time is shorter for the non-ionic surfactant and becomes longer as the acid content in the water increases, and for smaller anions of equal charge. 相似文献
10.
O.M. Matos G. A. Torchia G. M. Bilmes J. O. Tocho H. F. Ranea-Sandoval 《Applied physics. B, Lasers and optics》2005,80(4-5):535-539
The origin of the acoustic signals that are generated in the bulk of a KDP crystal during irradiation with short UV laser pulses is determined. The generation of these signals by excitation with moderate or high optical fluences is linked to the evolution of the population of point defects that is generated in the crystal by absorption of two UV photons. These defects are bleached due to their efficient linear absorption of UV radiation, and their non-radiative relaxation is shown to be the origin of the acoustic signals. The rate constants for the different processes involved in both the linear and the non-linear interactions were determined from the experiments presented here. Characteristic values for the quantum efficiency for the generation of defects, F = 0.95 ± 0.05, and for the quantum efficiency for bleaching of defects, B = 0.065 ± 0.005, were obtained for 266-nm laser radiation. The model developed for the intensity of the acoustic signals reproduces the experimental facts with very good accuracy. 相似文献