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2.
R. L. S. Devine C. T. Foxon B. A. Joyce J. B. Clegg J. P. Gowers 《Applied Physics A: Materials Science & Processing》1987,44(2):195-200
Beryllium diffusion during MBE growth of (Al, Ga)As layers, (Al, Ga)As/GaAs heterojunctions and GaAs/AlAs superlattices has been studied by electrochemical C-V and secondary ion mass spectrometry (SIMS) concentration profiling, in conjunction with transmission electron microscopy. Diffusion times were comparatively short since they were limited to part of the growth sequence, so non-equilibrium effects had a significant influence. The results are consistent with an interstitial-substitutional mechanism in which lattice site incorporation becomes more difficult with increasing band gap enthalpy. Incorporation involves a kick-out reaction which leads to the observed disordering of the superlattices. 相似文献
3.
A scaleable synthesis of 2-bromo-3-fluorobenzonitrile via the NaOMe-catalyzed bromodeboronation of 2-cyano-6-fluorophenylboronic acid was developed. The generality of this transformation was demonstrated through the halodeboronation of a series of aryl boronic acids. Both aryl bromides and aryl chlorides were formed in good to excellent yields when the corresponding aryl boronic acid was treated with 1,3-dihalo-5,5-dimethylhydantoin and 5 mol % NaOMe. 相似文献
4.
The dissociation constants of carboxymethyloxysuccinic acid (CMOS) have been measured at 25° and an ionic strength of 0·1M in sodium perchlorate. The values found were: pK1 = 2·52, pK2 = 3·77 and pK3 = 5·00. CMOS is thus seen to be rather stronger than its isomer citric acid. 相似文献
5.
The structural changes produced by oxidation and reduction of a silver surface in 1 M CKl with and without illumination were examined by scanning electron microscopy. Laser illumination (632.8 nm) during the oxidation-reduction cycle (ORC) produces a surface covered with a high density of sub-μm sized particles. The silver particles are the result of the photolytic reduction of the silver chloride made possible by the presence of the applied electric field within the silver chloride layer which prevents the recombination of the photoelectrons and holes. As the maximum anodization voltage of the ORC is increase to +100 mV vs. SCE, the number of photolytically produced silver particles increases. As the maximum anodization voltage is increased from +100 mV to +200 mV, the individual particle size increases from ≈200 nm to ≈800 nm. The intensity of Raman scattering from water adsorbed on the silver surface was maximized by a laser illuminated ORC with a maximum anodization voltage of +100 mV.Since recent theoretical studies indicate an optimum particle size of r≈50 nm for maximizing the electromagnetic component of the enhancement, the present results indicate that either the individual silver particles contain small scale (≈50 nm) roughness features or the electromagnetic factors are not the sole contributors to the enhancement. 相似文献
6.
M.W.C. Dharma-wardana A.H. MacDonald G.C. Aers D.J. Lockwood W.T. Moore R.L.S. Devine 《Superlattices and Microstructures》1987,3(6)
Results of Raman scattering experiments on (a) periodic superlattices made up of GaAs/InxGa1−xAs layers with high indium concentrations, (b) GaAs/Ga1−xAlxAs Fibonacci superlattices, are presented. We discuss the observed peak positions and intensities using the continuum theory of acoustic wave propagation in layered media and the photo-elastic coupling model. 相似文献
7.
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
8.
R.A.B. Devine 《Solid State Communications》1973,13(7):935-938
A recent interpretation of the crystal field ground state of Dy3+ in Pd is discussed in terms of a model where isotropic conduction electron/ion exchange is included. The new results suggest the ratio of fourth and sixth order crystal field parameters to be 292±4. The magnitude of the crystal field parameters cannot be determined. A resonance originating possibly from Dy ions in non-cubic sites is identified. 相似文献
9.
The results of electron paramagnetic resonance experiments on Mn diluted in zinc single crystals are reported showing a small anisotropy in the g-factor. The g-factor anisotropy correlates well with that found from susceptibility measurements. Comments are made upon the interpretation of the susceptibility data. 相似文献
10.