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141.
The 2S electron bubble placed in liquid helium has been previously believed to be spherical. We show that the 2S bubble is morphologically unstable at pressures above -1.23 bars. The 2S state being known to be radially unstable at pressures below -1.33 bars, the result leaves only a very narrow pressure range in which it can be found in a spherical configuration. Our stability analysis indicates that the 2S bubble is unstable against perturbations proportional to any of the third spherical harmonics Y(3m). Our numerical simulations show that there exist nonspherical stable configurations, such as the ones Maris and Konstantinov predicted for the 1P, 1D, and 2P electron bubbles and confirmed experimentally for the 1P. We believe that the 2S bubbles can also be produced and that our prediction will yield itself to experimental verification. 相似文献
142.
Carbanion addition to vinylogous acid triflates triggers carbon-carbon bond cleavage to form alkynyl ketones under mild conditions. Mechanistic factors affecting the cleavage event and its relationship to complementary fragmentations are discussed. A range of tethered keto-alkynes are obtained by a unified approach. 相似文献
143.
The copper-catalyzed reaction of isocyanides (CNCH2EWG1) 1 with electron-deficient alkynes (RC[triple bond]CEWG2) 2 gave the 2,4-di-EWG-substituted pyrroles 3 selectively, whereas the phosphine-catalyzed reaction of 1 with 2 afforded the 2,3-di-EWG-subsituted pyrroles 4. Accordingly, regioselective synthesis of substituted pyrroles has been achieved by merely choosing the catalyst. 相似文献
144.
Yasuji Yamada Sukeji Suzuki Kazuo Iguchi Hiroyuki Kikuchi Haruo Horiai Fumio Shibayama 《Tetrahedron letters》1980,21(40):3911-3914
The relative and absolute stereochemistry of two 13-membered carbocyclic cembranolides was determined as shown in and on the basis of NMR spectral evidence. 相似文献
145.
Polyhalogenated anthraquinones such as perfluoroanthraquinone, 1,2,3,4-tetrafluoroanthraquinone, and 1,2,3,4-tetrachloroanthraquinone are photoreduced in ethanol via direct electron transfer from ethanol. A dramatic switch-over from hydrogen-atom abstraction to electron transfer is induced by mixing ofππ with nπ* states in their T1 state and the enhanced electron-accepting character of polyhalogenated anthraquinones. 相似文献
146.
Kanetada Nagamine Kusuo Nishiyama Jun Imazato Hisayoshi Nakayama Masayuki Yoshida Yoichi Sakai Haruo Sato Takeshi Tominaga 《Chemical physics letters》1982,87(2):186-191
The relaxation rate of muonium in pure water has been found to be smaller than 0.05 × 106 s?1. With the aid of pulsed muong. μSR and MuSR measurements have been carried out over a longer time range than ever achieved. The results indicate a stability of thermal muonium in water from 3 to 29°C. 相似文献
147.
Near-infrared and visible reflectance spectrum was measured on the tetrathiafulvalene-chloranil (TTF-CA) crystal at temperatures in the range of 40–290 K. An abrupt change of reflectivity was found at about 80 K, and new dispersions associated with the intramolecular transitions of TTF+ and CA? gradually grew up on lowering temperature below 80 K, indicating the increase of the ionized fraction. 相似文献
148.
A criterion for stability of a charged sphere is obtained by use of two different methods. The result is applied to a charged dust in order to investigate its stability. 相似文献
149.
A temperature-dependent dielectric behavior is observed on Würster's blue perchlorate (TMPD+·ClO4) around its phase transition temperature. Soft modes of the lattice vibration are suggested to be the cause of this dielectric constant anomaly. 相似文献
150.