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991.
A. Schaufuß P. Roßbach I. Uhlig R. Szargan 《Analytical and bioanalytical chemistry》1997,358(1-2):262-265
The systems galena/2-mercaptobenzothiazole (MBT) and pyrite/MBT have been studied using synchrotron radiation excited photoelectron spectroscopy (SRXPS). The chemisorption of MBT and the multilayer formation of 2,2′-dithiobis(benzothiazole) (BBTD) are evidenced by additional structures, observed beside the substrate signals, in the S2p-spectra of cleaved mineral surfaces after adsorption of MBT. The amount of the complex remains constant at concentrations as high as 10–5 mol/L whereas the amount of BBTD increases. From the dependence of the adsorbate intensities on the excitation energy the conclusion can be drawn that an overlayer of BBTD on a chemisorbed layer of MBT is formed. The very weak adsorption of MBT on pyrite in alkaline solutions may explain the selective flotation of galena from pyrite in alkaline media. 相似文献
992.
P. Bunton M. Binkley G. Asbury 《Applied Physics A: Materials Science & Processing》1997,65(4-5):411-417
Received: 21 May 1997/Accepted: 4 July 1997 相似文献
993.
12 , 169 (1987). Reasonably good agreements in the peak output power and laser efficiency have been achieved. Model calculations
also predict that an efficiency as high as 2.7% can be obtained once the conditions of the above-mentioned experiments have
been optimized. From the consideration that the skin depth effectively limits the absorption length of the microwave pumping
and hence the excitable volume, it is concluded that high input power densities (>2 MW/cm3) and higher gas pressures (between 3 and 10 atm) are the preferable conditions to achieve higher efficiency. Preliminary
calculations on CCl4 containing XeCl gas mixtures show that improvement in laser efficiency by several folds may be achieved as a result of the
higher intrinsic efficiency of excimer formation.
Received: 23 September 1996 / Revised version: 25 March 1997 相似文献
994.
Quenching of fluorescence from Na(32
P) and K(42
P) atoms by various collision partners was studied at 973 and 1273K. Excited alkali atoms were produced photolytically by excimer
laser light at 193nm. For each collision pair, the appropriate relative velocity was computed and used to evaluate the quenching
cross-section from the measured rate constants. Cross sections for CO2, O2 and N2 are large (10–60Å2) while for Ar, the values are <1 Å2. The results are compared with those of previous investigations as a function of relative velocity. Finally, implications
for combustion diagnostics are briefly discussed.
Received: 29 March 1996 相似文献
995.
A method was developed for the determination of largest Lyapunov index for short chaotic time sequences with allowance for
the presence of noise in the response of the system. For this purpose a simple unidimensional representation modelling the
dynamics of irregular self-oscillations was investigated. Conditions were found for adequate determination of the largest
Lyapunov index from the noise-distorted signals. The results were used to obtain the largest Lyapunov index for the Belousov—Zhabotinskii
reaction taking place in an ideal-mixing closed reactor and in a constant-mixing flow-type reactor.
Institute of Organic Chemistry, National Academy of Sciences of Ukraine. Translated from Teoreticheskaya i éksperimental’naya
Khimiya, Vol. 33, No. 3, pp. 136–142, May–June, 1997. 相似文献
996.
We consider a pseudoparabolic variational inequality in a cylindrical domain semibounded in a variable t. Under certain conditions imposed on the coefficients of the inequality, we prove theorems on the unique existence of a solution
for a class of functions with exponential growth as t → ∞.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 7, pp. 919–929, July, 1998. 相似文献
997.
The mechanism of silicon epitaxy on porous Si(111) layers is investigated by the Monte Carlo method. The Gilmer model of adatom
diffusion extended to the case of arbitrary surface morphology is used. Vacancies and pendants of atoms are allowed in the
generalized model, the activation energy of a diffusion hop depends on the state of the neighboring positions in the first
and second coordination spheres, and neighbors located outside the growing elementary layer are also taken into account. It
is shown that in this model epitaxy occurs by the formation of metastable nucleation centers at the edges of pores, followed
by growth of the nucleation centers along the perimeter and the formation of a thin, continuous pendant layer. Three-dimensional
images of surface layers at different stages of epitaxy were obtained. The dependence of the kinetics of the epitaxy process
on the amount of deposited silicon is determined for different substrate porosities.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 512–517 (10 April 1998) 相似文献
998.
In this paper, a geometric connection between the joint numerical range and the numerical range for selfadjoint matrix polynomial is presented. Moreover, algebraic properties for these ranges are investigated. 相似文献
999.
Apart from specific methods amenable to specific problems, symplectic Runge-Kutta methods are necessarily implicit. The aim
of this paper is to construct explicit Runge-Kutta methods which mimic symplectic ones as far as the linear growth of the
global error is concerned. Such method of orderp have to bepseudo-symplectic of pseudosymplecticness order2p, i.e. to preserve the symplectic form to within ⊗(h
2p
)-terms. Pseudo-symplecticness conditions are then derived and the effective construction of methods discussed. Finally, the
performances of the new methods are illustrated on several test problems. 相似文献
1000.
G. G. Bondarenko A. I. Bazhin A. P. Korzhavyi V. I. Kristya R. D. Aitov 《Technical Physics》1998,43(9):1121-1122
The electric field at the surface of a charge spot created by an ion beam on a dielectric coating of a target is calculated.
An expression is obtained which relates the surface potential of the insulator to the potential of the collector corresponding
to saturation of the collector secondary-electron current. It permits determination of the potential drop across the oxide
layer of a cold cathode without introducing complications in the construction of the experimental apparatus.
Zh. Tekh. Fiz. 68, 126–128 (September 1998) 相似文献