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Differential cross sections for the scattering of D2O (velocity selected beam) by Ar (nozzle beam) were measured at kinetic energies, ē, of 13·5 × 10-14 erg? and 17·0 × 10-14 erg by the crossed molecular beam technique. The distributions were compared with differential cross sections calculated from Lennard-Jones (12, 6) and Kihara-Stockmayer trial potentials to determine the potential parameters. 相似文献
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Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial
multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant
motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons
are constantly heated by ECR technique in the presence of magnetic field. In this paper it has been shown theoretically that
how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation
of the multipole magnetic field [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole field is discussed
to some extent. And it is seen that it is not beyond the capability of the scientific community in the present scenario of
the advanced technology. Presently, it can be achieved for lesser field and slightly larger size of the multipole electromagnet
and can be used for improvement of the ECR ion source (ECRIS). 相似文献
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Amit Sur Joel L. Lebowitz J. Marro M. H. Kalos S. Kirkpatrick 《Journal of statistical physics》1976,15(5):345-353
The site-percolation problem on a simple cubic lattice is studied by the Monte Carlo method. By combining results for periodic lattices of different sizes through the use of finite-size scaling theory we obtain good estimates forp
c (0.3115±0.0005), (0.41±0.01), (1.6±0.1), and(0.8±0.1). These results are consistent with other studies. The shape of the clusters is also studied. The average surface area for clusters of sizek is found to be close to its maximal value for the low-concentration region as well as for the critical region. The percentage of particles in clusters of different sizesk is found to have an exponential tail for large values ofk forP <p
c. Forp >p
c there is too much scatter in the data to draw firm conclusions about the size distribution.Work supported in part by USAFOSR Grant #73-2430B and by ERDA #E(11-1)-3077. 相似文献
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We show that a small perturbation periodic in imaginary time can be used to compute expectation values of nondifferential operators that do not commute with the Hamiltonian within the framework of quantum diffusion Monte Carlo. Some results for the harmonic oscillator and the helium atom are presented showing the validity of the proposed method. 相似文献
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We report results of computer simulations of a three-dimensional lattice gas of interacting particles subject to a uniform external fieldE. The dynamics of the system is given by hoppings of particles to nearby empty sites with rates biased for jumps in the direction ofE. As for the two-dimensional system we find that here too there exists a critical temperature,T
c
(E) such that forT < T
c
(E) the systems orders in a very anisotropic phase with striplike typical configurations parallel to the field.T
c
(E) increases withE but substantially less strongly than in two dimensions. There is a break in the slope of the saturation current atT
c
(E). Our data are consistent with the critical exponent being mean field. 相似文献
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O. Penrose J. Lebowitz J. Marro M. Kalos J. Tobochnik 《Journal of statistical physics》1984,34(3-4):399-426
We make a quantitative comparison between the predictions of the Becker-Döring equations and computer simulations on a model of a quenched binary A-B alloy. The atoms are confined to the vertices of a simple cubic lattice, interact through attractive nearest neighbor interactions, and move by interchanges of nearest neighbor pairs (Kawasaki dynamics). We study in particular the time evolution of the number of clusters of A atoms of each size, at four different concentrations: A=0.035, 0.05, 0.075, and 0.1 atoms per lattice site. The temperature is 0.59 times the critical temperature. At this temperature the equilibrium concentration of A atoms in the B-rich phase is
A
eq
=0.0145 atoms/lattice site. The coefficients entering the Becker-Döring equations are obtained by extrapolation from previously published low-density calculations, leaving the time scale as the only adjustable parameter. We find good agreement at the three lower densities. At 10% density the agreement is, as might be expected, less satisfactory but still fairly good-indicating a quite wide range of utility for the Becker-Döring equations.Supported in part by NSF Grant DMR81-14726 and DOE Contract DE-AC02-76ERO3077. 相似文献