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971.
C.?Montero A.?González Ure?aEmail author J.?O.?Cáceres M.?Morato J.?Najera H.?J.?Loesch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,26(3):261-264
We report on a novel phenomenon observed during the passage of a pulsed NO beam seeded in He through a combined homogeneous, static electric and RF field, denoted as C-field in a standard molecular beam electric resonance (MBER) experiment. Although we refrain from the state selective A- and B-fields, which are considered crucial for a MBER experiment, the transmitted intensity exhibits as a function of the RF frequency conspicuous dips at resonance frequencies that depend strictly linearly on the static field strength E
0. Their spectral width is by a factor of 4 smaller than the time of flight broadening. Both, the resonance frequencies and their linear field dependence can be precisely predicted applying a simple expression for the Stark effect to a
transition of a single rotational state (J = 3/2) of the electronic ground state
. However, this formula is valid only in the high field limit (E
0 > 1000 kV/m) while the employed field (E
0 = 1.47 kV/m) was in the extreme low field domain where the large
type doubling and hyperfine coupling lead to a purely quadratic Stark effect. We assume that the phenomenon is due to a yet unknown collective rather than to an isolated particle process.Received: 9 May 2003, Published online: 12 August 2003PACS:
33.20.Bx Radio-frequency and microwave spectra - 32.60. + i Zeeman and Stark effects
Author for correspondence: A. González Ureña 相似文献
972.
Sampedro B Crespo P Hernando A Litrán R Sánchez López JC López Cartes C Fernandez A Ramírez J González Calbet J Vallet M 《Physical review letters》2003,91(23):237203
The onset of ferromagnetism has been experimentally observed in small Pd particles of average diameter 2.4 nm. High-resolution studies reveal that a high percentage of the fcc particle exhibits single and multiple twinning boundaries. The spontaneous magnetization close to 0.02 emu/g seems to indicate that only a small fraction of atoms holds a permanent magnetic moment and contributes to ferromagnetism. The possible origin of ferromagnetism is briefly discussed according to different models recently reported. 相似文献
973.
Investigation of the influence of humidity on the ultrasonic agglomeration of submicron particles in diesel exhausts 总被引:8,自引:0,他引:8
Riera-Franco de Sarabia E Elvira-Segura L González-Gómez I Rodríguez-Maroto JJ Muñoz-Bueno R Dorronsoro-Areal JL 《Ultrasonics》2003,41(4):277-281
Removing very fine particles in the 0.01-1 micro m range generated in diesel combustion is important for air pollution abatement because of the impact such particles have on the environment. By forming larger particles, acoustic agglomeration of submicron particles is presented as a promising process for enhancing the efficiency of the current filtration systems for particle removal. Nevertheless, some authors have pointed out that acoustic agglomeration is much more efficient for larger particles than for smaller particles. This paper studies the effect of humidity on the acoustic agglomeration of diesel exhausts particles in the nanometer size range at 21 kHz. For the agglomeration tests, the experimental facility basically consists of a pilot scale plant with a diesel engine, an ultrasonic agglomeration chamber a dilution system, a nozzle atomizer, and an aerosol sampling and measuring station. The effect of the ultrasonic treatment, generated by a linear array of four high-power stepped-plate transducers on fumes at flow rates of 900 Nm(3)/h, was a small reduction in the number concentration of particles at the outlet of the chamber. However, the presence of humidity raised the agglomeration rate by decreasing the number particle concentration by up to 56%. A numerical study of the agglomeration process as a linear combination of the orthokinetic and hydrodynamic agglomeration coefficients resulting from mutual radiation pressure also found that acoustic agglomeration was enhanced by humidity. Both results confirm the benefit of using high-power ultrasound together with humidity to enhance the agglomeration of particles much smaller than 1 micro m. 相似文献
974.
First-principles molecular-dynamics simulations have been performed for the liquid-vapor interfaces of liquid Li, Mg, Al, and Si. We analyze the oscillatory ionic and valence electronic density profiles obtained, their wavelengths, and the mechanisms behind their relative phase shift. 相似文献
975.
In this short note we give a characterization of extremal principally polarized abelian varieties determining an isolated point in Sing
The case g = 5 is treated in depth.Received: 14 June 2004 相似文献
976.
Grasp Embedded Scatter Search for the Multicommodity Capacitated Network Design Problem 总被引:1,自引:0,他引:1
Ada?M.?AlvarezEmail author José?Luis?González-Velarde Karim?De-Alba 《Journal of Heuristics》2005,11(3):233-257
A GRASP embedded Scatter Search is developed for the multicommodity capacitated network design problem. Difficulty for this problem arises from the fact that selection of the optimal network design is an NP-complete combinatorial problem. There exist no polynomial exact algorithms which can solve this problem in a reasonable period of time for realistically sized instances. In such cases, heuristic procedures are commonly used. Two strategies were designed for GRASP: a traditional approach and a memory based technique. As for Scatter Search, 5 different strategies were used to update the reference set. Computational results on a large set of randomly generated instances show the convenience of the proposed procedures. 相似文献
977.
J.?M.?MatíasEmail author W.?González-Manteiga M.?Francisco-Fernández C.?Ordó?ez 《Journal of Mathematical Modelling and Algorithms》2005,4(3):237-252
In this work, we apply variographic techniques from spatial statistics to the problem of model selection in local polynomial
regression with multivariate data. These techniques permit selection of the kernel and smoothing matrix with less computational
load and interpretation of the regularity of the regression function in different directions. Moreover, they may represent
the only feasible alternative for problems of a certain dimensionality. 相似文献
978.
Lapierre A Jentschura UD Crespo López-Urrutia JR Braun J Brenner G Bruhns H Fischer D González Martínez AJ Harman Z Johnson WR Keitel CH Mironov V Osborne CJ Sikler G Soria Orts R Shabaev V Tawara H Tupitsyn II Ullrich J Volotka A 《Physical review letters》2005,95(18):183001
The lifetime of the Ar13+ 1s(2)2s(2)2p2p0(3/2) metastable level was determined at the Heidelberg Electron Beam Ion Trap to be 9.573(4)(5). The accuracy level of one per thousand makes this measurement sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM) and to relativistic electron-electron correlation effects like the frequency-dependent Breit interaction. Theoretical predictions, adjusted for the EAMM, cluster about a lifetime that is approximately shorter than our experimental result. 相似文献
979.
Characterization of a 20 kHz sonoreactor. Part I: analysis of mechanical effects by classical and numerical methods 总被引:1,自引:0,他引:1
Sáez V Frías-Ferrer A Iniesta J González-García J Aldaz A Riera E 《Ultrasonics sonochemistry》2005,12(1-2):59-65
Numerical simulations have been carried out in order to characterize the ultrasonic field propagation and to obtain the spatial distribution of the mechanical effect derived from it. The results have been compared with those obtained with different classical physical methods (calorimetry, aluminium foil erosion, thermal probes) and have given useful information about the influence of the presence of probes and auxiliary tools in the ultrasonic field. All these information have been used for the development of the Part II of this work: analysis of chemical effects, providing an accurate picture of the reaction environment in the sonoreactor used (20 kHz, 100 W supplied by Undatim) for further uses in sonoelectrochemical studies. 相似文献
980.
Carrera E García T Céspedes A González I Fernández A Asensio LM Hernández PE Martín R 《Journal of AOAC International》2000,83(2):341-346
Raw and smoked samples of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the p53 gene. DNA from S. salar and 0. mykiss was amplified by using primers flanking exons 5 to 6 of the p53 nuclear gene. PCR products of different length were obtained for each species (532 and 518 base pairs, respectively). Sequences of PCR products obtained from S. salar and O. mykiss were compared in the search for polymorphic restriction sites. The restriction fragments obtained with Eco RV, Hinf I, and Taq I endonucleases showed interspecific polymorphism, making it a useful method for identification of Atlantic salmon and rainbow trout. 相似文献