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41.
After the conformation I was clarified to 5α-,10α,-cis-solidagolactones by 1H NMR measurement with Eu(dpm)3 and chemical transformations, the CD homoallylic benzoate chirality method was applied to the homoallylic alcohol system of solidagolactone IV () for a chiroptical determination of the absolute configuration. The result agreed with absolute configuration elucidated by x-ray analysis, indicating the usefulness of the cd method. 相似文献
42.
The split-off band exciton of silicon has been observed in the absorption spectrum by using a wavelength modulation technique. The spin-orbit splitting of the valence band is determined to be 44.1 ± 0.3 meV at 1.8 °K. The structures associated with some two-phonon indirect transitions have also been observed in the absorption spectrum. 相似文献
43.
Ohne Zusammenfassung 相似文献
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It is shown that an analysis of the wavelength modulated absorption spectrum enables us to estimate the transition matrix elements in indirect absorption. The transition matrix elements in silicon are determined to be for indirect absorption with the TO phonon, for the LO phonon and 0.0178 for the TA phonon. 相似文献
46.
A glycine receptor is involved in the organization of swimming movements in an invertebrate chordate
Background
Rhythmic motor patterns for locomotion in vertebrates are generated in spinal cord neural networks known as spinal Central Pattern Generators (CPGs). A key element in pattern generation is the role of glycinergic synaptic transmission by interneurons that cross the cord midline and inhibit contralaterally-located excitatory neurons. The glycinergic inhibitory drive permits alternating and precisely timed motor output during locomotion such as walking or swimming. To understand better the evolution of this system we examined the physiology of the neural network controlling swimming in an invertebrate chordate relative of vertebrates, the ascidian larva Ciona intestinalis. 相似文献47.
Miao J Chen CC Song C Nishino Y Kohmura Y Ishikawa T Ramunno-Johnson D Lee TK Risbud SH 《Physical review letters》2006,97(21):215503
In combination of direct phase retrieval of coherent x-ray diffraction patterns with a novel tomographic reconstruction algorithm, we, for the first time, carried out quantitative 3D imaging of a heat-treated GaN particle with each voxel corresponding to 17 x 17 x 17 nm3. We observed the platelet structure of GaN and the formation of small islands on the surface of the platelets, and successfully captured the internal GaN-Ga2O3 core shell structure in three dimensions. This work opens the door for nondestructive and quantitative imaging of 3D morphology and 3D internal structure of a wide range of materials at the nanometer scale resolution that are amorphous or possess only short-range atomic organization. 相似文献
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We report on photocarrier transport of high-growth-rate microcrystalline Si (μc-Si) in conjunction with the lateral size, σL, of crystallites’ conglomerate (grain) determined from the atomic force microscope (AFM) topographic images on the basis of fractal concepts. μc-Si films were prepared using very-high-frequency plasma-enhanced chemical vapor deposition at a high deposition rate of 6.8 ± 0.5 nm/s. μc-Si thicknesses, d, were varied from 0.53 μm to 5.6 μm. With an increase in d, σL increased from 70 nm to 590 nm. At the same time, the ambipolar diffusion lengths, Lamb, of photocarriers, observed using the steady-state photocarrier grating (SSPG) technique, increased from 50 nm to 420 nm. Log–log plots of Lamb versus d and σL versus d were both expressed as a power law with an exponent of 0.9, yielding a simple linear relation between Lamb and σL. Moreover, their ratio, Lamb/σL, was below unity, implying the intra-grain carrier diffusion. From these results, the role of the grain (column) boundaries for photocarrier diffusion in μc-Si is discussed. 相似文献
50.
Intramolecular hydrogen atom tunneling in 2-chlorobenzoic acid has been investigated by low-temperature matrix-isolation infrared spectroscopy with the aid of density functional theory calculation. Infrared spectra of two relatively stable syn isomers, SC and ST, were observed in argon and xenon matrixes. When the matrix samples were annealed after deposition, the isomerization from ST to SC occurred around the benzene-carboxyl bond. Two less stable anti isomers, AT, which has an OH...Cl intramolecular hydrogen bond, and AC, which has no OH...Cl bond, were produced from SC and ST upon UV irradiation. When the matrix samples were kept in the dark after UV irradiation, AT and AC changed to ST and SC, respectively, by spontaneous isomerization around the C-O axis in the carboxyl group. The rate constants of isomerization, AT --> ST, in a Xe matrix were estimated from the absorbance changes at various matrix temperatures. The rate constants showed a drastic decrease in deuteration of the hydrogen atom of the carboxyl group. The relationship between the rate constants and the matrix temperature did not follow the Arrhenius law. These findings lead to the conclusion that the isomerization of AT --> ST and AC --> SC in low-temperature rare-gas matrixes proceeds through intramolecular hydrogen atom tunneling. 相似文献