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61.
S. Berkebile G. Koller A.J. Fleming P. Puschnig C. Ambrosch-Draxl K. Emtsev T. Seyller J. Riley M.G. Ramsey 《Journal of Electron Spectroscopy and Related Phenomena》2009,174(1-3):22
Recently, there have been reports of the valence band photoemission of pentacene films grown on various substrates with particular emphasis on the highest occupied molecular orbital (HOMO) and its dispersion. In various works, evidence for HOMO band dispersion as high as 0.5 eV, even for polycrystalline films, has been presented. In apparent contradiction to these results, we have previously reported a band dispersion of only 50 meV, measured on a well characterised film with a single polymorph and single crystalline orientation, 5A(0 2 2). Here, we first present the two-dimensional momentum distribution of the HOMO of a 5A(0 2 2) film. Then the development of the valence band spectra for films grown at room temperature and low temperature are compared, and we show that morphological aspects can lead to the apparent observation of high HOMO dispersion. Finally, with the aid of the two-dimensional momentum distribution of the HOMO, we show that a reasonably large dispersion (0.25 eV) does indeed exist in 5A(0 2 2). 相似文献
62.
Bulman–Fleming Sydney 《代数通讯》2013,41(3):951-964
The tree main results of this paper deal with the generating vectors of simple infinite and finite dimesional modules arising as composition factors of the Kac modules K↓ G 0 and K of the Lie superalgebra sl(m/n). 相似文献
63.
64.
J. R. Kempton M. Senba D. J. Arseneau A. C. Gonzalez J. J. Pan A. Tempelmann D. M. Garner D. G. Fleming 《Hyperfine Interactions》1991,65(1-4):801-809
Results of muon polarization studies in xenon and argon up to 60 atm are reported. In argon for pressures up to 10 atm, the
muon polarization is best explained by an epithermalcharge exchange model. Above this pressure, the decrease inP
D and increase inP
L are ascribed to charge neutralization and spin exchange reactions, respectively, in the radiolysis track. Measurements with
Xe/He mixtures with a xenon pressure of 1 atm indicate that the lost polarization in the pure xenon at this pressure is due
to inefficient moderation of the muon. As the pressure in pure xenon is increased above 10 atm, we find thatP
L remains roughly constant andP
D begins to increase. The lost fraction may be due to the formation of a XeMu Van der Waals type complex, whileP
D is ascribed to XeMu+ formation. This suggests that spur processes appear to be less important in xenon than in argon. 相似文献
65.
A route to meta-benzenocyclophanes containing four tetrazole rings in the macrocycle is described. 相似文献
66.
67.
A twin-hole optical fiber with pure synthetic silicate glass between the two electrode holes was thermally poled. The induced second-order nonlinearity (SON) was located at the core-cladding interface sections that were nearly parallel to the poling electric field. The polarization dependence of the induced SON suggests that nonlinearity was due to the presence of a space-charge field, which was probably formed by electron migration among the defects located at the core-cladding interface. The magnitude of the induced SON was measured to be approximately 0.06 pm /V. 相似文献
68.
69.
P.G. Fleming J.D. Holmes D.J. Otway M.A. Morris 《Journal of solid state chemistry》2011,184(9):2595-2600
Mixed oxide solid solutions are becoming ever more commercially important across a range of applications. However, their synthesis can be problematical. Here, we show that ceria-lanthana solid solutions can be readily prepared via simple precipitation using hexamethylenetetramine. However, the solution chemistry can be complex, which results in the precipitated particles having a complex structure and morphology. Great care must be taken in both the synthesis and characterisation to quantify the complexity of the product. Even very high heat treatments were not able to produce highly homogeneous materials and X-ray diffractions reveals the non-equilibrium form of particles prepared in this way. Unexpected crystal structures are revealed including a new metastable cubic La2O3 phase. 相似文献
70.
Using TMPZnCl·LiCl as a kinetically highly active base, nitriles and esters undergo a Pd-catalyzed α-arylation under mild conditions. Remarkably, in the case of α,β- or β,γ-unsaturated nitriles, a regioselective γ-arylation or a γ-alkenylation is observed. 相似文献