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NICOLE R. BRINKMANN JONATHAN C. RIENSTRA-KIRACOFE HENRY F. SCHAEFER III 《Molecular physics》2013,111(8):663-675
Electron affinities of ethylene and six cyano-substituted ethylenes (cyanoethylene, 1, 1-dicyanoethylene, cis-1, 2-dicyanoethylene, trans-1, 2-dicyanothylene, tricyanoethylene, and tetracyanoethylene) were determined using six different density functional or hybrid Hartree-Fock/density functional methods. Equilibrium geometries and harmonic vibrational frequencies for each species were determined with each density functional method. Experimental electron affinities exist for three of the six systems studied (cyanoethylene, trans-1, 2-dicyanoethylene, and tetracyanoethylene); for the three systems, the absolute average EA errors for the different methods are 0.10eV (BLYP), 0.19ev (BHLYP), 0.22eV (B3LYP), 0.20eV (BP86), 0.78eV (B3P86), and 0.81eV (LSDA). The electron affinities of gem-dicyanoethylene, cis-discyanoethylene, and tricyanoethylene are not known from experiment but are predicted here to be 1.23eV (gem-dicyanoethylene), 1.32eV (cis-dicyanoethylene), and 2.41eV (tricyanoethylene). Contrary to earlier suggestions, tetracyanoethylene is predicted to be planar, rather than twisted. Density functional theory predicts that the 2B1u state of the ethylene anion lies lower than the 2B2g state, which is reported by experimentalists as the (transient) ground state, and lower than the 2Ag state. Coupled-cluster results indicate that the 2Ag state is lower than either the 2B2g or 2B1u states. The energetic stabilization of cyano substitution on ethylene results from the π and π? conjugation of multiple cyano groups. The HOMO-LUMO gap in ethylene decreases with increasing cyano substitution, from 7.2eV in C2H4 to 3.8eV in C2(CN)4, explaining the extreme difference between the electron affinities of ethylene (negative) and tetracyanoethylene (~T3.0eV). 相似文献
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J. Sauvage F. Ibrahim B. Roussière J. Genevey A. Gizon G. Marguier P. Kilcher A. Knipper R. Béraud G. Căta-Danil F. Le Blanc J. Obert J. Oms J. C. Putaux C. Richard-Serre A. Wojtasiewicz NICOLE Collaborations 《The European Physical Journal A - Hadrons and Nuclei》2005,25(1):5-21
Low-spin states of 184Au have been studied using the β+/EC decay of 184Hg. γ-ray and conversion-electron singles spectra were recorded with 184Hg mass-separated sources. For γ-γ-t and X-γ-t coincidence measurements, mercury nuclei were produced in the 148Sm + 40Ar reaction and transported by a He-jet system. The electron spectra were recorded from 184Hg sources produced at ISOLDE. A level scheme of 184Au including 48 transitions is proposed. The experimental results are interpreted in the frame of a semi-microscopic axial-rotor-plus-two-quasiparticle model developed in the context of the HF+BCS approximation. 相似文献
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K. Schlösser I. Berkes E. Hagn P. Herzog T. Niinikoski H. Postma C. Richard-Serre J. Rikovska N. J. Stone L. Vanneste E. Zech the ISOLDE Collaboration NICOLE ISOLDE Collaboration 《Hyperfine Interactions》1988,43(1-4):139-149
A facility for Nuclear Implantation into Cold On-Line Equipment (NICOLE) is being installed at the new on-line isotope separator
ISOLDE 3 at CERN. The first on-line run was in the beginning of July 1988. The low temperature equipment has been successfully
tested and first off-line experiments on various isotopes have been performed. NMR/ON has been done on vaious isotopes (Co,
Xe, Pt, Au) in iron host. First experience with the top-loading dilution refrigertor (Oxford Instruments Limited) shows that
it performs very well. The cooling power is 400 μW at 100 mK and 34 μW at 25 mK. The base temperature can be kept continuously
well below 5 mK. NMR/ON can be performed at temperatures below 5.5 mK. The base temperature on-line is expected to be lower
then 6 mK. The sample can be cooled down from room temperature to 10 mK within two hours, to 6 mK within 3 hours which is
not only important for off-line but also for on-line experiments when samples have to be changed to remove long lived daughter
activity. The latest results will be reported. 相似文献
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