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911.
V. G. Arhipkin V. P. Timofeev I. V. Timofeev 《Radiophysics and Quantum Electronics》2004,47(10-11):811-817
The effect of spatial localization of the atomic (Raman) coherence in the forbidden transition of a three-level atom is studied for two intense optical pulses with comparable Rabi frequencies. We propose to use this effect for coherent recording of intense optical pulses. Various schemes of reading of the recorded pulse are considered. 相似文献
912.
A.P. Yalin 《Applied physics. B, Lasers and optics》2004,78(3-4):477-483
The quantitative effects of laser lineshape on signals from cavity-enhanced absorption spectroscopy (CEAS) and integrated cavity output spectroscopy (ICOS) experiments are examined. The governing equations for CEAS signals including the laser lineshape are derived. Approximations under which the laser lineshape may be neglected or replaced with an effective lineshape are presented. It is shown that the laser lineshape effects may be parameterized with two dimensionless variables: the laser linewidth normalized by the absorption linewidth, and the peak sample absorbance normalized by the mirror loss. In terms of the dimensionless variables, we simulate CEAS and ICOS signals and the absorbances inferred from them. The simulation results provide a useful tool for CEAS and ICOS practitioners to gauge the importance of laser lineshape effects in specific experiments. Simulations are performed for the four combinations of Gaussian and Lorentzian lineshapes for the laser and the absorption. PACS 42.62.Fi; 78.40.-q; 32.70.Jz 相似文献
913.
The three-dimensional structure of the calcite (104)-water interface has been determined with surface X-ray scattering. Nine crystal truncation rods (including specular and non-specular rods) were measured providing both vertical and lateral sensitivity to the interfacial structure. The results reveal that calcite is nearly ideally terminated with a single surface hydration layer that includes two inequivalent water molecules having distinct heights of 2.3 ± 0.1 and 3.5 ± 0.2 Å, each with a well-defined lateral registry with respect to the calcite surface. No additional layering of water is observed beyond this surface hydration layer. Small displacements in the outer two calcium carbonate layers were also observed. These results are compared with previous experimental and computational results. 相似文献
914.
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
915.
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
916.
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
917.
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
918.
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
919.
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
920.
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