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81.
Sørensen JK Fock J Pedersen AH Petersen AB Jennum K Bechgaard K Kilså K Geskin V Cornil J Bjørnholm T Nielsen MB 《The Journal of organic chemistry》2011,76(1):245-263
In continuation of previous studies showing promising metal-molecule contact properties a variety of C(60) end-capped "molecular wires" for molecular electronics were prepared by variants of the Prato 1,3-dipolar cycloaddition reaction. Either benzene or fluorene was chosen as the central wire, and synthetic protocols for derivatives terminated with one or two fullero[c]pyrrolidine "electrode anchoring" groups were developed. An aryl-substituted aziridine could in some cases be employed directly as the azomethine ylide precursor for the Prato reaction without the need of having an electron-withdrawing ester group present. The effect of extending the π-system of the central wire from 1,4-phenylenediamine to 2,7-fluorenediamine was investigated by absorption, fluorescence, and electrochemical methods. The central wire and the C(60) end-groups were found not to electronically communicate in the ground state. However, the fluorescence of C(60) was quenched by charge transfer from the wire to C(60). Quantum chemical calculations predict and explain the collapse of coherent electronic transmission through one of the fulleropyrrolidine-terminated molecular wires. 相似文献
82.
Potential Analysis - In this paper we study the sequence of orthonormal polynomials {Pn(μ;z)} defined by a Borel probability measure μ with non-polar compact support $S(\mu )\subset... 相似文献
83.
84.
E. Samsøe P. M. Petersen S. Andersson-Engels P. E. Andersen 《Applied physics. B, Lasers and optics》2005,80(7):861-864
A frequency-doubled laser diode system for generation of blue–UV light is described. The system is based on an external-cavity high-power laser diode with double feedback from the zeroth and the first orders of a diffraction grating. Light at 405 nm is generated in a single-pass configuration using periodically poled KTiOPO4. We show that the double grating feedback improves the second harmonic conversion efficiency by several orders of magnitude as compared to the freely running laser. The conversion efficiency may be improved further such that higher second-harmonic powers may be generated. 相似文献
85.
The paper presents a new approach to model validation and fault diagnosis problems for a class of uncertain systems in which the uncertainty is described by an integral quadratic constraint. The new approach is developed by applying methods from linear quadratic optimal control theory. This leads to a method for model validation and fault diagnosis which is based around a robust Kalman filter type structure. 相似文献
86.
Complex119Sn-vacancy defects in GaP have been studied by Mössbauer-emission spectroscopy on the 24-keV γ radiation of119Sn. The defects were created by ion implantations of radioactive119In+ and119Sb+, which in their decays both populate the Mössbauer state of119Sn. The radiogenic119Sn-vacancy defects are proposed to consist of substitutional119Sn on Ga or P sites, respectively, associated with (P or Ga) vacancies. 相似文献
87.
We study consequences of defining the impact parameter as being the variable conjugate to transverse relative c.m. momentum, p⊥. This coincides with a proposal originally made by Chang and Raman. The dynamical information carried by these are intimately connected to the behaviour of 90° scattering. In particular, impact parameter dynamics is a priori qualitatively different from direct channel angular momentum dynamics. A phenomenological study of elastic π±p and pp data at fixed values of longitudinal momentum, p6, leads to a generalized geometrical scaling hypothesis. In contrast with the power behaviour predicted by parton models, the data suggest exponential behaviour of the scaling amplitudes at fixed p6 of the type eRp⊥ with R ? 1 fm. Correspondingly these amplitudes are described by a pair of complex conjugate singularities on the imaginary axis in the impact parameter plane. 相似文献
88.
A simple and versatile pneumatically-operated two-layer rotary valve is described for simultaneous introduction of sample and diversion of analytical streams in flow injection analysis. Examples of application include valve configuration with time-controlled sample volume and with loop-controlled sample volumes in one or two loops; both configurations are useful in routine analyses of samples of highly varying analyte concentrations. The usefulness of the valve for ion-exchange preconcentration procedure is also demostrated. 相似文献
89.
J.F. Petersen 《Nuclear Physics A》1975,255(2):307-314
The two-proton transfer reaction (3He, n) has been measured on four gas targets, 16O, 18O, 20Ne, and 22Ne, with an incident 3He energy of 18.3 MeV. The data were taken with a neutron time-of-flight spectrometer in the angular range 0° to 40° c.m. The results for selected transitions are compared to DWBA predictions using shell-model spectroscopic amplitudes. In addition, the data for the 18O(3He, n)20Ne reaction are compared to predictions of the SU(3) strong coupling model. 相似文献
90.