J. Phys. I France
Volume 3, Numéro 6, June 1993
Page(s) 1405 - 1415
DOI: 10.1051/jp1:1993188
J. Phys. I France 3 (1993) 1405-1415

Oscillations in the reflectivity of a diffuse polymer layer. An analogy with the Ramsauer Townsend effect

G. Jannink

Laboratoire Léon Brillouin (CEA-CNRS), CE-Saclay, 91191 Gif-sur-Yvette Cedex, France Gorlaeus Laboratory, University of Leiden, Netherlands

(Received 23 December 1992, accepted in final form 5 February 1993)

The reflectivity of a diffuse, finite layer of adsorbed polymers is examined. If the bulk solution is semi-dilute, the screening structure generates oscillations in the reflectivity function in the vicinity of total reflexion. The deviation with respect to the Fresnel law increases with the depth of the layer. In the limit of infinite depth the reflectivity function displays the discontinuity first predicted by Schack (Thesis, Munich 1986) and first observed by Guiselin (Europhys. Lett. 17 (1992) 57). In our approach, we make use of earlier results obtained by Morse and Feshbach in their interpretation of the Ramsauer-Townsend effect of slow electrons scattered by heavy atoms.

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