排序方式: 共有34条查询结果,搜索用时 9 毫秒
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Dr. Maya Guillaumont Dr. Isabelle Fourré Dr. Julien Pilmé Dr. Stéphanie Halbert Prof. Hélène Gérard 《Chemphyschem》2021,22(8):788-795
An inner-sphere disproportionation mechanism of the Co(I) precursor CoCl(PPh3)3 is described through a Density Functional Theory study. The essential role of oleylamine in this process is unravelled. A detailed analysis of the electronic structure of Cobalt dimers of the general formula Co2Cl2Ln (L=NH3 and PH3) demonstrates that electron transfer is triggered by asymetric coordination of amine and phosphine to stabilize a mixed-valence Co(II)−Co(0) dimer. This is consistent with the HSAB statement that both amine and phosphine ligands are required to stabilize the reaction products, respectively Co(II) and Co(0) centers. We propose a quasi-athermic multi-step disproportionation mechanism with low activation barriers where the electron transfer goes through simple ligand exchanges between Co. 相似文献
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Fragmentation mechanisms of ionized butylbenzene to give m/z 91 and m/z 92 fragment ions have been examined at the G3B3 and G3MP2B3 levels of theory. It is shown that the energetically favored pathways lead to tropylium, Tr(+), and methylene-2,4-cyclohexadiene, MCD(?+), ions. Formation of m/z 91 benzyl ions, Bz(+), by a simple bond fission (SBF) process, needs about 30 kJ/mol more energy than Tr(+). Possible formation of C(7)H(8)(?+) ions of structures different from the retro-ene rearrangement (RER) product, MCD(?+), has been also considered. Comparison with experimental data of this "thermometer" system is done through a kinetic modeling using Rice-Ramsperger-Kassel-Marcus (RRKM) and orbiting transition state (OTS) rate constant calculations on the G3MP2B3 0 K energy surface. The results agree with previous experimental observation if (i) the competitive formation of Tr(+) and Bz(+) is taken into account in the m/z 91 pathway, and (ii) the stepwise character of the RER fragmentation is introduced in the m/z 92 fragmentation route. 相似文献
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O. Andersen R. Bauer G.B. Hagemann M.L. Halbert B. Herskind M. Neiman H. Oeschler H. Ryde 《Nuclear Physics A》1978,295(1):163-188
Reactions between 18O and 16O ions, with energies well above the Coulomb barrier, and 148, 150Nd target nuclei were used to study the cascades of γ-rays in the residual nuclei 161, 162Er. A multi-counter setup was used in which the γ-rays were detected by a Ge(Li) counter coupled in coincidence with up to 9 NaI(Tl) counters. The γ-multiplicity has been studied for γ-rays cascading through states above and along the yrast line. Higher moments of the multiplicity distributions (shape parameters) were deduced from the data. These moments allow the construction of the spin distribution for the entry states. The difference between these spin distributions from reactions induced by 16O and 18O ions was studied. Also the fusion cross section was measured for the two systems as a function of bombarding energy and compared to the multiplicity results at two different excitation energies (Ex = 49.5 and 56.2 MeV). A subtraction technique has been applied in the data analysis with the intention to study the decay of a selected part of the high-spin region, and the results show besides the 4n channel an unexpected large contribution of the 5n channel from this region. The sidefeeding patterns of the multiplicity distributions are extracted and show a significant difference for the 16O and 18O induced reactions, especially at the lowest bombarding energies. The results are compared with statistical model calculations. 相似文献
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Gómez Del Campo J Galindo-Uribarri A Beene JR Gross CJ Liang JF Halbert ML Stracener DW Shapira D Varner RL Chavez-Lomeli E Ortiz ME 《Physical review letters》2001,86(1):43-46
Radioactive ion beams of 17F were used to study several resonance states in 18Ne. Clear evidence for simultaneous two-proton emission from the 6.15 MeV state (Jpi = 1(-)) in 18Ne has been observed with the reaction 17F+1H. Because of limited angular coverage, the data did not differentiate between the two possible mechanisms of simultaneous decay, diproton (2He) emission or direct three-body decay. The two-proton partial width was found to be 21+/-3 eV assuming 2He emission and 57+/-6 eV assuming three-body decay. The total width of the 1(-) state was measured to be 50+/-5 keV. Several additional resonances that decay by single proton emission were also studied. 相似文献
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