排序方式: 共有83条查询结果,搜索用时 62 毫秒
41.
Clark SC Walz JY Ducker WA 《Langmuir : the ACS journal of surfaces and colloids》2004,20(18):7616-7622
We describe the use of evanescent wave scattering to measure the separation between the surface of a solid and a particle that is attached to an atomic force microscope (AFM) cantilever. Termed evanescent wave atomic force microscopy, our approach involves measuring the intensity of the light scattered from an evanescent field formed by the total internal reflection of a laser beam at a solid/fluid interface. In a conventional AFM "colloid probe" measurement, this separation must be inferred from an examination of the surface forces. Direct measurement of this separation with an evanescent wave atomic force microscope (EW-AFM) removes some ambiguity in the surface force measurement and, in addition, allows new types of measurements. For example, the force can be monitored at a constant separation. Our evanescent scattering apparatus is essentially identical to that used in total internal reflection microscopy (TIRM), except that we collect the light that scatters back into the incident medium, because the AFM partly obscures the forward scattered light (i.e., light scattered into the transmitted region). Compared to a conventional TIRM measurement, where the particle moves freely, attaching the particle to the cantilever in an EW-AFM gives much greater control of the particle position. 相似文献
42.
McKee CT Clark SC Walz JY Ducker WA 《Langmuir : the ACS journal of surfaces and colloids》2005,21(13):5783-5789
We describe measurements of the scattering of visible light from an evanescent field by both spherical particles (R = 1-10 mum) that are glued to atomic force microscopy (AFM) cantilevers, and by sharp tips (R < 60 nm) that were incorporated onto the cantilevers during manufacture. The evanescent wave was generated at the interface between a flat plate and an aqueous solution, and an atomic force microscope was used to accurately control the separation, h, between the particle and the flat plate. We find that, for sharp tips, the intensity of scattered light decays exponentially with separation between the tip and the plate all the way down to h approximately 0. The measured decay length of scattered intensity, delta, is the same as the theoretical decay length of the evanescent intensity in the absence of the sharp tip. For borosilicate particles, (R = 1-10 mum), the scattering also decays exponentially with separation at large separations. However, when the separation is less than roughly 3delta, the measured scattering intensity is smaller in magnitude than that which would be predicted by extrapolating the exponential decay observed at large separations. For these particles, the scattering approximately fits the sum of two exponentials. The magnitude of the deviation from exponential at contact was roughly 10-15% for R = 1 mum particles and about 30% for larger particles and is larger for s-polarized light. Preliminary experiments on polystyrene particles shows that the scattering is also smaller than exponential at small separations but that the deviation from exponential is larger for p-polarized light. In evanescent wave AFM (EW-AFM) the scattering-separation can be calibrated for situations where the scattering is not exponential. We discuss possible errors that could be introduced by assuming that exponential decay of scattering continues down to h = 0. 相似文献
43.
T. A. Armstrong I. J. Bloodworth J. N. Carney R. Childs B. R. French B. Ghidini J. B. Kinson V. Lenti A. Palano G. Vassiliadis O. Villalobos Baillie M. F. Votruba G. Zito R. Zitoun WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,35(2):167-171
In a search for glueballs and exotic states decaying into baryons and antibaryons we have investigated the production of baryon antibaryon pairs produced centrally in the reactions π+/pp → π+/p(X 0)p at 85 GeV/c. In particular, channels whereX 0 goes to \(p\bar p,p\bar p\pi ^ + \pi ^ - ,p\bar p2\pi ^ + 2\pi ^ - \) and \(\Lambda \bar \Lambda \) have been observed. No significant new structure is observed in the mass spectra. 相似文献
44.
The WA Collaboration 《The European Physical Journal C - Particles and Fields》2005,41(3):287-296
The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in 208Pb + 208Pb collisions at 158
GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a Fourier analysis. For both the photon and charged particle distributions the first two Fourier coefficients are observed to decrease with increasing centrality. The observed anisotropies of the photon distributions compare well with the expectations from the charged particle measurements for all centralities.Received: 22 May 2004, Revised: 14 April 2005, Published online: 4 May 2005PACS:
25.75.Dw 相似文献
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47.
G. Gerbier D. Bertrand J. Guy P. Marage M. Aderholz N. Armenise J. H. Bartley J. P. Baton V. Brisson R. Belusevic D. Brou F. W. Bullock M. Calicchio E. F. Clayton T. Coghen A. M. Cooper-Sarkar O. Erriquez P. J. Fitch P. O. Hulth G. T. Jones P. Kasper H. Klein C. Kochowski M. Lagraa S. Leighton-Davis R. Middleton D. B. Miller M. M. Mobayyen D. R. O. Morrison M. Neveu S. Nuzzo S. O'Neale M. A. Parker P. Petiau J. Sacton R. A. Sansum N. Schmitz E. Simopoulou M. Talebzadeh K. Varvell C. Vallee A. Vayaki W. Venus H. Wachsmuth J. Wells W. Wittek E. Zevgolatakos BEBC WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,29(1):15-28
A sample of over 25,000 fully measured neutrino and antineutrino charged current interactions in BEBC includes 192 dilepton candidates. The prompt signal after subtraction of background is 41 ±7µ+ e -, 35±7µ+µ- events from \(\bar v\) interactions, and 32±7µ-µ+ events from ν interactions. There are 2 trileptons, µ-µ- e + and µ-µ-µ+. Results are compared with other experimental data and with the standard model. Limits to prompt like sign µ+ e +, µ+µ+ and µ-µ- signals are given and compared with other experiments and with theoretical calculations. 相似文献
48.
ZHU XiaoSong CHENG Liang LU Lin & TENG Bin State Key Laboratory of Coastal Offshore Engineering Dalian University of Technology Dalian China School of Civil Resource Engineering The University of Western Australia Perth WA Australia Centre for Deepwater Engineering Dalian 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
The Moving Particle Semi-implicit (MPS) method performs well in simulating violent free surface flow and hence becomes popular in the area of fluid flow simulation. However, the implementations of searching neighbouring particles and solving the large sparse matrix equations (Poisson-type equation) are very time-consuming. In order to utilize the tremendous power of parallel computation of Graphics Processing Units (GPU), this study has developed a GPU-based MPS model employing the Compute Unified Device Ar... 相似文献
49.
X Zhang MH Uddin H Yang G Toikka W Ducker N Maeda 《Langmuir : the ACS journal of surfaces and colloids》2012,28(28):10471-10477
Contamination has previously been invoked to explain the flat shape and the long lifetimes of interfacial nanobubbles (INBs). In this study, the effects of surfactants on the formation and the stability of INBs were investigated when surfactants were added to the system before, during, and after the standard solvent exchange procedure (SSEP) for the formation of INBs. The solutions of sodium dodecyl sulfate (SDS) above critical micelle concentration were found to have little effect on the bubble stability. Likewise, cleaning of the substrate with a surfactant solution had little effect. In contrast, addition of a water-insoluble surfactant during the formation dramatically reduced the INBs. Finally, repeated application of SSEP to surfactant-coated substrates progressively rinsed the surfactant off the system. Thus, we found no evidence to support the hypothesis that (1) INBs are stabilized by a layer of insoluble organic contaminant or that (2) SSEP introduces surface-active materials to the system that could stabilize INBs. 相似文献
50.
Marijke WA de Backer Carlos P Fitzsimons Maike AD Brans Mieneke CM Luijendijk Keith M Garner Erno Vreugdenhil Roger AH Adan 《BMC neuroscience》2010,11(1):81