Beitrag zur Deutung der anomalen optischen Eigenschaften feinstteiliger Metallkolloide in gro�er Konzentration

Abstract

Die vorliegende Untersuchung beschreibt ein Verfahren, nach dem man erstmalig den L~iillfaktor dtinner, im Hochvakuum aufgedampfter Schichteii eines Metallkolloides direkt ermi~tela kann. Trotz eines ungew6hiilich grof3en experimeiitellen Aufwandes kaiiI1 der Ftillfaktor yon Kolloidschichteii mit eiiier Dicke yon etwa 100 ~ nur bis aiif einen mittleren relativeii Fehler voii 15~ angegeben werden.

Glass-Ceramics and Photo-Sitalls

“…The following expression has been obtained [761] for the plasma frequency Wo of spherical colloidal particles: w~ = 11.J(ne 2 /me), where n is the density of the electrons taking part in plasma vibrations, m is the electron mass, e is the electron charge, and e is the optical dielectric constant of the medium in which the particle is located. Thus, the plasma frequency depends basically on the bulk concentration of the electrons taking part in collective vibrations.…”

Optical properties of colloidal gold nanoparticles implemented into a subsurface layer of fused silica

“…These defects can fuse into micropores, and their concentration is expected to reach its maximum just in the silica subsurface layer. The first reason for that is a thermal gradient that causes preferential occurrence of defects within the low-temperature areas [3]. The second reason is that the thermal minimum at the stage of laser irradiation appears to be directly under the gold granules, since gold reflects almost completely the irradiating CO 2 -laser beam.…”

“…a possibility for exciting plasmons (or a so-called surface plasmon resonance), are useful for implementing a number of modern analytical methods [1][2][3]. Simultaneously, new composite materials such as granular films placed in the layer of bulk substance have also conditioned a surge of interest [4].…”

“…Simultaneously, new composite materials such as granular films placed in the layer of bulk substance have also conditioned a surge of interest [4]. The island films inside the matrices of solid materials have been obtained, e.g., through ion implantation [5], sol-gel technology [6], and a combined evaporation of base and metal [3]. Nevertheless, these methods reveal some drawbacks, including technological difficulties that arise while obtaining colloids with preset optical properties.…”

“…Hence, the data obtained from both the spectrophotometic and the atomic-force microscopic measurements show that the granules differ slightly in their diameter and, therefore, the classical model developed in Refs. [3][4][5] can be readily applied for their description. According to this model, the self-resonant electron frequency in a granule can be written as…”