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61.
We have studied the feature of the resonant light scattering (RLS) spectra from polycrystalline ZnTe films of different crystallite size by exciting above the fundamental absorption edge. It is found that decreasing the crystalline size, higher order LO Raman-like lines are quenched due to increase in the nonradiative damping of exciton-like polaritons as intermediate states of RLS. 相似文献
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Much is known about the connection between the growth and decayof subharmonic functions. The results indicate that there isa general principle: asubharmonic function cannot decay toofast relative to its growth.Three theorems are provedwhich, together with work previously published elsewhere, givea fairly complete account of how this principle works out fora subharmonic function having extremal decay along a ray. 1991Mathematics Subject Classification: 30D20, 31A05. 相似文献
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Suppose that a consistent one-step numerical method of orderr is applied to a smooth system of ordinary differential equations.Given any integer m 1, the method may be shown to be of orderr + m as an approximation to a certain modified equation. Ifthe method and the system have a particular qualitative propertythen it is important to determine whether the modified equationsinherit this property. In this article, a technique is introducedfor proving that the modified equations inherit qualitativeproperties from the method and the underlying system. The techniqueuses a straightforward contradiction argument applicable toarbitrary one-step methods and does not rely on the detailedstructure of associated power series expansions. Hence the conclusionsapply, but are not restricted, to the case of Runge-Kutte methods.The new approach unifies and extends results of this type thathave been derived by other means: results are presented forintegral preservation, reversibility, inheritance of fixed points.Hamiltonian problems and volume preservation. The techniquealso applies when the system has an integral that the methodpreserves not exactly, but to order greater than r. Finally,a negative result is obtained by considering a gradient systemand gradient numerical method possessing a global property thatis not shared by the associated modified equations. 相似文献
67.
Mereacre V Ako AM Clérac R Wernsdorfer W Hewitt IJ Anson CE Powell AK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(12):3577-3584
The reaction of [Mn6O2(Piv)(10)(4-Me-py)(2.5)(PivH)(1.5)] (1) (py: pyridine, Piv: pivilate) with N-methyldiethanolamine (mdeaH2) and Ln(NO3)3 x 6 H2O in MeCN leads to a series of nonanuclear compounds [Mn5Ln4(O)6(mdea)2(mdeaH)2(Piv)6(NO3)4(H2O)2]2 MeCN (Ln=Tb(III) (2), Dy(III) (3), Ho(III) (4), Y(III) (5)). Single-crystal X-ray diffraction shows that compounds 2-5 are isostructural, with the central core composed of two distorted {Mn(IV)Mn(III)Ln2O4} cubanes sharing a Mn(IV) vertex, representing a new heterometallic 3d-4f motif for this class of ligand. The four new compounds display single-molecule magnet (SMM) behaviour, which is modulated by the lanthanide ion used. Moreover, the values found for Delta(eff) and tau(o) for 3 of 38.6 K and 3.0 x 10(-9) s respectively reveal that the complex 3 exhibits the highest energy barrier recorded so far for 3d-4f SMMs. The slow relaxation of the magnetisation for 3 was confirmed by mu-SQUID measurements on an oriented single crystal and the observation of M versus H hysteresis loops below 1.9 K. 相似文献
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Shiri Farshad Norouzibazaz Mohammadsaleh Yari Ako Taherpour Avat 《Structural chemistry》2018,29(5):1465-1474
Structural Chemistry - Semustine as an anti-cancer medicine is decomposed by hydrolysis under pH-dependent conditions, forming chlorocarbonium ion and interaction with nucleic acid molecules. This... 相似文献
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Avat Arman Taherpour Ako Yari Fatemeh Ghasemhezaveh Mohammad Ali Zolfigol 《Journal of the Iranian Chemical Society》2017,14(12):2485-2493
The efficiently oxidized various types of 2-substituted imidazolines to the corresponding imidazoles using potassium permanganate supported on silica gel (KMnO4/SiO2) under mild conditions and at room temperature have been reported before. In this study, the competitive concerted, catalytic stepwise (E 1 cb′ Cat .) and E 1 cb′ mechanisms of the oxidative aromatization process of 2-imidazolines to the corresponding imidazoles using KMnO4/SiO2 have been theoretically investigated by DFT-B3LYP/6-31G** method. The achieved data from this computational study confirmed that the reaction occurs by stepwise E 1 cb′ mechanism on the basis of the anomeric effect. 相似文献
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Ayuk M. Ako Jonathan P. Hill Christopher E. Anson Katsuhiko Ariga Annie K. Powell 《Journal of Coordination Chemistry》2016,69(21):3182-3191
A new heterodonor chelating ligand, 2-{[bis(2-pyridylmethyl)amino]methyl}-4-(n-dodecyl)-6-methylphenol (HL2), has been synthesized and employed in the preparation of two amphiphilic heteroleptic mononuclear complexes, [FeIII(L2)(Br)2] (1) and [FeIII(L2)(SCN)2] (2). Compound 1 was obtained by reaction of HL2 with FeBr3 in EtOH. In situ reaction of Fe(L2)Br2 (1) with KSCN in EtOH or refluxing pure crystalline 1 with excess KSCN in EtOH/CH2Cl2 afforded 2. The complexes were characterized by elemental analysis, infrared spectroscopy, and X-ray single-crystal structural determination. Magnetic studies carried out exclusively on 2 to check for spin crossover suggest that the compound has a ground spin state of 5/2 and maintains high spin throughout the temperature range studied. 相似文献