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991.
Beamstrahlung is studied for bunches with densities that are transversely non-uniform. By treating an interesting special case analytically, one elicits the consequences of the new stationary phase conditions. Focusing effects are found to be relatively unimportant on the global radiated rate. Results are compared with the previously known case of uniform cylindrical bunches. 相似文献
992.
Kellen Chen Yi‐Ming Cheng Dr. Yun Chi Prof. Mei‐Lin Ho Chin‐Hung Lai Pi‐Tai Chou Prof. Shie‐Ming Peng Prof. Gene‐Hsiang Lee 《化学:亚洲杂志》2007,2(1):155-163
We have prepared and characterized a series of osmium complexes [Os2(CO)4(fpbpy)2] ( 1 ), [Os(CO)(fpbpy)2] ( 2 ), and [Os(fpbpy)2] ( 3 ) with tridentate 6‐pyrazol‐3‐yl 2,2′‐bipyridine chelating ligands. Upon the transformation of complex 2 into 3 through the elimination of the CO ligand, an extremely large change in the phosphorescence wavelength from 655 to 935 nm was observed. The results are rationalized qualitatively by the strong π‐accepting character of CO, which lowers the energy of the osmium dπ orbital, in combination with the lower degree of π conjugation in 2 owing to the absence of one possible pyridine‐binding site. As a result, the energy gap for both intraligand π–π* charge transfer (ILCT) and metal‐to‐ligand charge transfer (MLCT) is significantly greater in 2 . Firm support for this explanation was also provided by the time‐dependent DFT approach, the results of which led to the conclusion that the S0→T1 transition mainly involves MLCT between the osmium center and bipyridine in combination with pyrazolate‐to‐bipyridine 3π–π* ILCT. The relatively weak near‐infrared emission can be rationalized tentatively by the energy‐gap law, according to which the radiationless deactivation may be governed by certain low‐frequency motions with a high density of states. The information provided should allow the successful design of other emissive tridentate metal complexes, the physical properties of which could be significantly different from those of complexes with only a bidentate chromophore. 相似文献
993.
Bei Sheng KANG Ling Hong WENG Liang Ren HUANG Xue Tai CHEN Han Qin LIU Jia Xi LU 《中国化学快报》1990,1(1):79-80
Compound(PH4P)[V3MP6](MPH2=o-HOC6H4SH)was obtained by reaction of VCl3 and Na2MP in ethanol in the presence of PH4PBr.It is triclinic and crystallizes in space group P1, fw=1237.3, a=14.127(4), b=14.342(4), c=15.878(4)Å;α=65.08(2), β=73.09(2), γ=78.68(2)°;V=2781.3 Å3, Z=2, dc=1.48 g/cm3.Final R factor is 0.063.The three vanadium atoms are linearly arranged and bridged by the oxygen atoms and terminally chelated by the thiolato-atoms of the six MP2-ligands in pseudo-S6 symmetry. 相似文献
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We study dual or complementary variational principles for functionals with deviating argument and discontinuous extremals. Local conditions for the existence of a pair of dual extremum principles are given. Results are then applied to the control problem involving linear neutral differential-difference equations. 相似文献
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