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1.
Z. P. Hu Z. X. Shen L. Qin S. H. Tang M. H. Kuok G. Q. Xu K. F. Mok H. H. Huang 《Journal of Molecular Structure》1995,356(3):163-168
The high-pressure Raman studies of 7,7,8,8-tetracyanoquinodimethane (TCNQ) single crystals and polycrystalline CuTCNQ are presented in this paper. TCNQ shows a phase transition at 22 kbar, a pressure higher than reported earlier. CuTCNQ undergoes a first order phase transition at 30 kbar, which is characterized by the abrupt disappearance of all the Raman bands. 相似文献
2.
The elastic vibrations of spherical nanoparticles have been widely studied by Raman scattering. However, there exist more than one set of selection rules for Raman scattering from these vibrations. For instance, Kanehisa has stated that only torsional modes with angular momentum l = 2 are Raman-active, while Tanaka et al. proposed that spheroidal modes of even l and torsional modes of odd l are Raman-active. These contradict selection rules of Duval which states that only spheroidal modes of l = 0 or 2 are Raman-active. Our present calculations based on a macroscopic model show that all torsional modes have vanishing intensity in the Raman spectrum. 相似文献
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Dr. Valerie H. L. Wong Dr. Sai V. C. Vummaleti Prof. Luigi Cavallo Dr. Andrew J. P. White Prof. Steven P. Nolan Dr. King Kuok Hii 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13320-13327
A general synthetic route was used to prepare 15 new N‐heterocyclic carbene (NHC)–AgI complexes bearing anionic carboxylate ligands [Ag(NHC)(O2CR)], including a homologous series of complexes of sterically flexible ITent ligands, which permit a systematic spectroscopic and theoretical study of the structural and electronic features of these compounds. The complexes displayed a significant ligand‐accelerated effect in the intramolecular cyclisation of propargylic amides to oxazolidines. The substrate scope is highly complementary to that previously achieved by NHC–Au and pyridyl–AgI complexes. 相似文献
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The way to determine the effective temperature of the excitonic system from the study of the edge luminescence high energy region is motivated. Experimental data on the exciton heating in ZnSe single crystals under laser excitation are presented. The effective temperature of excitons Tx has reached 158 K at the lattice temperature TL = 77 and the peak excitation intensity 2.7 MW cm?2 (hv0 = 3.50), while the excess temperature of the excitons (Tx ? TL) increases as a square root of the pump intensity. Exciton-hot-electron, exciton-hot-photon, exciton-exciton interactions and excitonic Auger process are considered as possible causes of the exciton system heating. 相似文献
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This study examines the difficulties college students experience when creating and interpreting graphs in which speed is one of the variables. Nineteen students, all preservice elementary or middle school teachers, completed an upper‐level course exploring algebraic concepts. Although all of these preservice teachers had previously completed several mathematics courses, including calculus, they demonstrated widespread misconceptions about the variable speed. This study identifies four cognitive obstacles held by the students, provides excerpts of their graphical constructions and verbal interpretations, and discusses potential causes for the confusion. In particular, misconceptions arose when students interpreted the behavior and nature of speed within a graphical context, as well as in situations where they were required to construct a graph involving speed as a variable. The study concludes by offering implications for the teaching and learning of speed and its interpretation within a graphical setting. 相似文献
9.
tert-Butyl perbenzoate is a substitute for benzoquinone for mild (room-temperature) Fujiwara-Moritani reactions between acetanilides and butyl acrylate under homogeneous conditions. The system was enhanced further by including Cu(OAc)(2) as a cocatalyst. Methyl methacrylate can be activated toward coupling under these conditions. 相似文献
10.
Vu Kuok Fong 《Ukrainian Mathematical Journal》1988,40(1):94-97
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 40, No. 1, pp. 110–113, January–February, 1988. 相似文献