Michael Sawodny

Photovolatilization of thin polysilane films detected by surface‐plasmon spectroscopy

Surface‐plasmon optical techniques (attenuated total internal reflection and surface plasmon microscopy, in particular) are employed to characterize the optical and structural properties of thin films of poly(methyl‐phenyl‐silane) in the thickness range d0=40–400 nm. Irradiation with deep UV light (90% at λ=253.7 nm) is shown to cause photovolatilization which results in a self‐development of illuminated areas. The time dependence of this etching process is investigated, and substantial differences between irradiation in air or in an Ar atmosphere of 10−3 MPa partial pressure are found: For 40‐nm‐thick films in the presence of oxygen an ablation rate of 1.3 nm/min is derived for the first 5–10 min which drops rather abruptly to zero (irradiation power density ∼0.4 mW/cm2 ). In Ar atmosphere the etching rate is ∼0.1 nm/min but constant for more than 1 h. UV‐absorption spectra and gel permeation chromatography are performed to gain some insight into the molecular mechanisms of these photochemical and photop...

Langmuir-Blodgett-Kuhn multilayer assemblies of liquid-crystalline azo-dye side chain homo- and copolymers

Abstract We report on the characterization of Langmuir-Blodgett-Kuhn (LBK) multilayer assemblies of novel liquid-crystalline (LC) side chain polymers containing azo dyes. The structure and optical properties of these materials were determined. Persistent and reversible optical data storage and possible molecular mechanism are discussed in this paper.

Novel optical techniques for the analysis of polymer surfaces and thin films

SummaryWe report on novel optical techniques, based on evanescent waves, for the characterization of polymer surfaces and thin films. We first describe photo-ablation studies with polysilane films investigated by surface plasmon microscopy, a technique which is particularly well-suited for ultrathin samples. Thicker films that are homogeneous enough to carry optical waveguide modes can be characterized with high lateral resolution by the recently developed waveguide microscopy. We demonstrate this for a thin film of a solid polyelectrolyte. Finally, we report on surface plasmon field-enhanced Raman-spectroscopic and -imaging investigations of ultrathin Langmuir-Blodgett-Kuhn-layers of cadmium arachidate.

Optical switching of azobenzene sidechain molecules observed by surface plasmon spectroscopy

The use of surface plasmons is reported for the optical characterization of thin organic films, in particular thin polymer films at a metal dielectric interface. The basic properties of PSP are presented, including excitation and the technique of surface plasmon microscopy, which allows to obtain an image. As an example studies are presented on the trans-cis photoisomerization of azobenzene sidechain polymers in ultra thin films, prepared by the Langmuir-Blodgett-Kuhn technique. The transition from the trans to the cis state induces a change in the refractive index of the film. These changes were detected and their kinetics measured by a surface plasmon spectroscopy technique. A refractive index pattern could be written into the films and the areas of different refractive indices have been detected by surface plasmon microscopy.

Optical Characterization of Ultrathin Polymer Films by Evanescent Light

This paper describes the use of evanescent light for the optical characterization of polymer thin films and interfaces. Firstly, a few basic concepts of evanescent wave phenomena, including total internal reflection, plasmon surface polaritons and guided optical modes, are reviewed. It is shown that the excitation of these waves allows for a sensitive determination of the optical architecture of the interface(s) involved. This “surface light” can then be used for the same broad range of optical techniques as it is known from experimental set-ups designed for the investigation of various optical properties of polymer samples using plane electromagnetic waves, i.e. “normal” photons. This is demonstrated for diffraction experiments and microscopic investigations. The examples given include thin polymer films prepared by spin-coating or by the Langmuir-Blodgett-Kuhn technique.