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1.
M. Dubé C. Daneault V. Vuorinen M. Alava M. Rost 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):15-26
We investigate the structure and dynamics of the interface between
two immiscible liquids in a three-dimensional disordered porous
medium. We apply a phase-field model that includes explicitly
disorder and discuss both spontaneous and forced imbibition.
The structure of the interface is dominated by a length scale
ξ× which arises from liquid conservation. We further show
that disorder in the capillary and permeability act on different
length scales and give rise to different scalings and
structures of the interface properties. We conclude with a
range of applications. 相似文献
2.
A. Labate N. R. Heckenberg R. Meucci M. Ciofini 《Applied physics. B, Lasers and optics》1993,56(5):307-311
Measurements of the pressure dependence of the relaxation rate of vibrationally excited molecules in the 119 m CH3OH laser have been correlated with the pressure and pump power dependence of the output power in the framework of a rate-equation model for which numerical and approximate analytical solutions have been obtained. Both diffusion and collisional de-excitation are important, and substantial deviations from thermal equilibrium populations are deduced, consistent with an operating pressure range which increases with pump power. 相似文献
3.
Dynamic characteristics of atomic force microscopy (AFM) cantilevers can be influenced by their working media. We perform an experimental study on the resonant responses of rectangular AFM cantilevers with different sizes immersed in various viscous fluids. The measured resonance frequencies in liquids are used to valldate several theoretical models. Comparison shows the analytical model proposed by Sader [J. Appl. Phys. 84 (1998) 64] can give the best agreement with the experimental results with the maximum relative error nearly 16% for all the cantilevers in different liquids. The ratio between the resonant frequencies in air and water is almost independent of the cantilever length, which is consistent with the theoretical analyses. 相似文献
4.
An All-Solid-State Tunable Dual-Wavelength Ti:Sapphire Laser with Quasi-Continuous-Wave Outputs 下载免费PDF全文
A high power dual-wavelength Ti:sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd:YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%. 相似文献
5.
Applying single- and double-pulse excitation at 800 nm, the kinetics of the upconversion fluorescence in the green, as well
as the upconversion laser at 543 nm was studied. No significant delay between the pumping pulse and the laser emission was
found. In the erbium doped (1000 ppm) optical fiber, the mechanism responsible for the upconversion is purely of the excited
state absorption (ESA) type. The double-pulse technique enables also a determination of the lifetime of the intermediate metastable
state 4
I
11/2 (7±0.3 ms). Some other basic properties of the upconverted fluorescence and of the laser itself (fluorescence spectrum, optical
gain, laser threshold) are also described.
Received: 11 December 2000 / Revised version: 18 February 2001 / Published online: 18 July 2001 相似文献
6.
We report two kinds of compact and efficient diode-end-pumped TEM00 lasers with output power >25 W at ≈50 W of incident pump power. One laser consists of a single 0.3 at. % Nd:YVO4 crystal in a V-type cavity, the other laser includes two 0.5 at. % Nd:YVO4 crystals in a linear cavity. Experimental results show that lowering Nd3+ concentration can be beneficial in extending the fracture-limited pump power but it also increases the sensitivity of the
pump wavelength due to the overlapping efficiency.
Received: 19 February 2000 / Revised version: 30 May 2000 / Published online: 20 September 2000 相似文献
7.
Mariana Köber Enrique Sahagún Martina Fuss Fernando Briones Mónica Luna Juan José Sáenz 《固体物理学:研究快报》2008,2(3):138-140
The effects of adhesion hysteresis in the dynamic‐dissipation curves measured in amplitude‐modulation atomic force microscopy are discussed. Hysteresis in the interaction forces is shown to modify the dynamics of the cantilever leading to different power dissipation curves in the repulsive and attractive regimes. Experimental results together with numerical simulations show that power dissipation, as measured in force microscopy, is not always proportional to the energy dissipated in the tip–sample interaction process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
Compact Single-Stage Femtosecond Multipass Ti:Sapphire Amplifier at 1 kHz with High Beam Quality 下载免费PDF全文
A compact femtosecond Ti:sapphire amplifier system is reported using single-stage multipass configuration with high beam quality. A high dispersion glass stretcher and a pair of double prisms for compression are introduced based on broadband femtosecond seed pulses. The non-grating-based pulse stretcher and compressor are advantageous to increase high beam quality and to reduce the high-order dispersion. A Gaussian filter is used to reduce the gain narrowing effect in amplification. The compact femtosecond Ti:sapphire nine-pass amplifier delivers pulses with a duration of 26 fs and an energy of 800μJ at 7mJ pumping pulses energy at I kHz. The 1-kHz femtosecond amplifier with high beam quality and high stability is very suitable for ultrafast physics research applications, such as attosecond science, ultra-precision micromachining, and THz wave generation. 相似文献
9.
All-Solid-State Nd:YAG Laser Operating at 1064nm and 1319nm under 885nm Thermally Boosted Pumping 下载免费PDF全文
We report a high-effciency Nd:YAG laser operating at 1064 nm and 1319nm, respectively, thermally boosted pumped by an all-solid-state Q-switched Ti:sapphire laser at 885 nm. The maximum outputs of 825.4 m W and 459.4mW, at 1064nm and 1319nm respectively, are obtained in a 8-ram-thick 1.1 at.% Nd:YAG crystal with 2.1 W of incident pump power at 885nm, leading to a high slope efficiency with respect to the absorbed pump power of 68.5% and 42.0%. Comparative results obtained by the traditional pumping at 808nm are presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power at 1064nm under the 885nm pumping are 12.2% higher and 7.3% lower than those of 808rim pumping. At 1319nm, the slope efficiency and the threshold with respect to the absorbed pump power under 885nm pumping are 9.9% higher and 3.5% lower than those of 808 nm pumping. The heat generation operating at 1064 nm and 1319 nm is reduced by 19.8% and 11.1%, respectively. 相似文献
10.
A. Vollkopf O. Rudow M. Müller-Wiegand G. Georgiev E. Oesterschulze 《Applied Physics A: Materials Science & Processing》2003,76(6):923-926
The thermal oxidation of structured silicon surfaces was successfully used to reproducibly define apertures of approximately
100 nm in silicon dioxide tips at reduced oxidation temperatures. In this paper we theoretically investigate the oxidation
process in more detail, describing the rheological behavior of silicon dioxide as a Maxwell fluid with non-linear viscosity.
For this purpose numerical calculations of the oxidation process of trench-like silicon structures were performed. Contrary
to former assumptions, our theoretical results indicate that oxide-growth retardation is more effective at raised oxidation
temperatures. This is experimentally confirmed in the case of trench structures. The more pronounced oxide retardation at
elevated temperatures is exploited to obtain apertures in silicon dioxide tips of 60 nm for oxidation temperatures of 1100 °C.
Received: 8 April 2002 / Accepted: 11 April 2002 / Published online: 4 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-561/804-4136, E-mail: oester@physik.uni-kassel.de 相似文献