摘要:

AbstractOptical experiments on the wetting properties of liquid4He and molecular hydrogen are reviewed. Hydrogen films on noble metal surfaces serve as model systems for studying triple point wetting, a continuous transition between wetting and non‐wetting. By means of optically excited surface plasmons, the adsorbed film thickness for temperatures around, and far below, the bulk melting temperature is measured, and the physical mechanisms responsible for the transition are elucidated. Possible applications for other experiments in pure and applied research are discussed. Thin films and droplets of liquid helium are studied on cesium surfaces, on which there is a first order wetting transition. Our studies concentrate on dynamical observations via surface plasmon microscopy, which provide insight into the morphology of liquid helium droplets spreading at different temperatures. Features corresponding to pinning forces, the prewetting line, and the Kosterlitz‐Thouless transition are clearly obser

ISSN:0003-3804    

DOI:10.1002/andp.19975090602

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn a first step we have tried to show that very probably in Quantumelectrodynamics (QED) due to vacuum polarization effects the original bare charges of electrons and positrons are smeared out so much that their original divergent energy distances from the vacuum energy become finite. Furthermore, we have sketched how one has to generalize the calculations to refine the considerations presented in this paper.

ISSN:0003-3804    

DOI:10.1002/andp.19975090603

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe explore the validity of the Vlasov equation as a semi‐classical approximation of time‐dependent Hartree‐Fock and time‐dependent LDA theories. We discuss theh→ 0 limit for the propagation of quantal wavefunctions in terms of classical densities. Theh→ 0 limit is studied formally by means of its Wigner and Husimi phase‐space representations. We consider an application to the valence electron cloud of metal clusters and show a comparison between quantal and Vlasov dynamics

ISSN:0003-3804    

DOI:10.1002/andp.19975090604

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe explore from a numerical point of view the validity of the Vlasov equation as a semi‐classical approximation of time‐dependent Hartree‐Fock and time‐dependent LDA theories, in terms of the survival of the Pauli principle. The fermionic properties are investigated by using a Na9+cluster as test case and solving the Vlasov equation with the test particle method. This allows to derive a time span for which the Vlasov equation provides an acceptable approx

ISSN:0003-3804    

DOI:10.1002/andp.19975090605

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0003-3804    

DOI:10.1002/andp.19975090601

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY