摘要:

AbstractAll relevant low‐energy transition amplitudes for theD(d,n)3HeandD(d,p)3Hreactions were determined from a fit to Legendre expansion coefficients of the available experimental data. A simple barrier penetrability model was used. QuintetS‐wave transitions are found to contribute strongly thus obliterating the idea of neutron‐lean “polarized” fusion energy production. TheD+Dinteraction radius was determined with good accuracy for both reactions individually. The astrophysicalSfunctions show a smallS‐wave enhancement andP‐wave suppression of theD

ISSN:0003-3804    

DOI:10.1002/andp.19935050602

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe far‐infrared reflection spectra of betaine phosphite single crystals in the three crystallographic directions are investigated in the range from 5 to 600 cm−1at temperatures between 203 and 323 K using a dispersive Fourier spectrometer. The dielectric function is evaluated from the complex amplitude reflection coefficient measured. In the spectrum polarized along the ferroelectric direction a soft mode of relaxation type is observed which accounts for a large part of the relevant static dielectric constant atTc= 210 K. Among the oscillator modes, which generally exhibit normal temperature dependence, there is a heavily overdamped mode at 58 cm−1, polarized along the crystallographiaa1axis, with anomalous damping behaviour. The damping constant decreases nearly linearly with temperature up to 323 K which is close toT= 355 K where a second phase transition is known to

ISSN:0003-3804    

DOI:10.1002/andp.19935050603

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe semiclassical approach of Onsager and Pippard has been very successful in relating the electronic properties of a normal metal to its band structure and fermi surface. This paper extends the method to a superconductor. A generalized London equation relating the supercurrent density to the vector potential is obtained, in terms of band and fermi surface parameters and an energy gap which may be anisotropic. The results allow an interpretation of measured penetration depths directly in terms of the electronic and gap structures of the superconductor. They lead to easy physical visualization of the origin of anisotropies and other features of measured penetration depths.

ISSN:0003-3804    

DOI:10.1002/andp.19935050604

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe motion of a quantum particle in a random potential with short‐range fluctuations is analyzed using a generalized mode‐coupling approximation. The original theory of Götze was extended by introducing a wave‐vector dependent current relaxation kernel. Here we apply the theory to the special case of exciton dynamics in a binary molecular crystal. We find a localization–delocalization transition in three dimensions with a critical exponent of 1 for the inverse localization length. In the intermediate time regime, our theory predicts a region of anomalous diffusion. This can be interpreted as a precursor to localization. At the transition point it leads to the known asymptotic low‐frequency behaviourD

ISSN:0003-3804    

DOI:10.1002/andp.19935050605

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA wide class of boundary problems in quantum mechanics is discussed by using path integrals. This includes motion in half‐spaces, radial boxes, rings, and moving boundaries. As a preparation the formalism for the incorporation of δ‐function perturbations is outlined, which includes the discussion of multiple δ‐function perturbations, δ‐function perturbations along perpendicular lines and planes, and moving δ‐function perturbations. The limiting process, where the strength of the δ‐function perturbations gets infinitely repulsive, has the effect of producing impenetrable walls at the locations of the δ‐function perturbations, i.e. a consistent description for boundary problems with Dirichlet boundary‐condition emerges. Several examples ill

ISSN:0003-3804    

DOI:10.1002/andp.19935050606

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0003-3804    

DOI:10.1002/andp.19935050601

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY