Die Bestimmung optischer Konstanten von Metallen durch Anregung von Oberflächenplasmaschwingungen

Abstract

The Determination of the Optical Constants of Metals by Excitation of Surface Plasmons A method is given to determine accurately the optical constants and the thickness of thin films when the real and the imaginary part of the dielectric constants obey the condition er < --1, gi <[er I-The method makes use of the possibility to excite surface plasma waves with the help of the inhomogeneous light wave obtained by total reflexion. The accuracy of the method is pointed out. As an example the optical constants of silver foils in the wavelength interval 4000 to 6000 A are determined. A. EinleitungUm den Realteil und den Imagin~irteil der dielektrischen Konstanten er, e~ zusammen mit der Schichtdicke yon dfinnen Schichten genau zu bestimmen, mul3 man eine Mel3methode verwenden, bei der die MeBwerte empfindlich und in verschiedener Weise von drei genannten Parametern abh~ingen.In ~ ist gezeigt, dab in der Umgebung der Plasmafrequenz yon Metallen (e~0) die Transmission von parallel zur Einfallsebene polarisiertem Licht bei verschiedenen Winkeln gtinstige Funktionen in diesem Sinne sind. Man nutzt dabei das Phgnomen der ,,Plasmaresonanzabsorption" der ,,strahlenden" Oberfl~ichenschwingungen aus. Wie man auch die Resonanzabsorption der zweiten Art der Obeffl~ichenplasmaschwingungen, der sog. ,,nicht strahlenden", benutzen kann, um sehr genaue optische Konstanten zu erhalten, wird in dieser Arbeit angegeben. In ghnlicher Weise kann man auch durch Streulichtmessungen die Plasmaresonanzemission dazu benutzen, genaue optische Konstanten zu bestimmen 2.Die nicht strahlenden Oberfl/ichenschwingungen k6nnen an der Grenzfl~iche zwischen MetaU und Vakuum auftreten, wenn die komplexe Dielektrizit/itskonstante des Metalls e=er+iel der Bedingung gentigt ~,<-1, ~e< I~1. Sie sind dadurch charakterisiert, dab die Komponente

Electrochemical Surface Plasmon Resonance Spectroscopy at Bilayered Silver/Gold Films

“…To better represent the signal enhancement, we use the following coefficient Q: (2) where Δθ Ag/Au and Δθ Au correspond to the maximal SPR signals associated with Cu 2+ electroreduction at the Ag/Au substrate and at the Au substrate, respectively. Figure 3 is a plot of Q vs. the Ag/Au thickness ratio.…”

Experimental methods for investigating protein adsorption kinetics at surfaces

“…Non-radiative propagating charge density waves can exist at the surface of a metal characterized by a complex permittivity e M = € M + ie M provided that the conditions 4 < -1 (76) and 141 > e c = "c (77) are fulfilled (Kretschmann, 1971;Agranovich & Mills, 1982;Lukosz, 1991). These surface plasmons or polaritons are />-polarized electromagnetic waves propagating parallel to a metal-dielectric interface with wave vector k M x given by:…”

“…17) is to evaporate a thin film of a nobel metal (Au, Ag, Pt etc. in order to avoid the formation of a tarnishing film) on the surface of a hemicylindrical prism (Kretschmann, 1971) or a diffraction grating (Cullen et al 1987/88). The intensity of the reflected beam is monitored as a function of the angle of incidence onto the prism or the grating.…”

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High-resolution surface plasmon resonance sensor with Fano resonance in waveguide-coupled multilayer structures

“…[1][2][3][4] The arrangement of SPR sensors usually employs attenuated total reflection (ATR), which is based on prism coupling as an optical excitation method. 5) The two most frequently used coupling methods are the Kretschmann 6) and Otto configurations.…”