EPR of Mo5+ in amorphous MoO3 thin films

Mo⁵⁺ centres in amorphous thin films of MoO₃ have been studied as a function of optical density using EPR techniques. Measurements were made for over an order of magnitude change in optical density and down to helium temperatures. A direct correlation between the optical density and the number of Mo⁵⁺ centres is found for low optical densities but further colouration does not continue to increase the number of Mo⁵⁺ centres. A model is proposed to explain the results.     

A note on a core catcher of a cooperative game

In Driessen (1986) it is shown that for games satisfying a certain condition the core of the game is included in the convex hull of the set of certain marginal worth vectors of the game, while it is conjectured that the inclusion holds without any condition on the game. In this note it is proved that the inclusion holds for all games.

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Zusammenfassung In Driessen (1986) wurde für Spiele, die eine gewisse Bedingung erfüllen, gezeigt, da\ der Kern des Spieles in der konvexen Hülle von gewissen Vektoren der Marginalwerte liegt. Es wurde vermutet, da\ diese Inklusion ohne weitere Bedingung an das Spiel gilt. In dieser Note wird nun gezeigt, da\ die Inklusion für alle Spiele gilt.

     

Solution concepts ofk-convexn-person games

For any positive integersk andn, the subclass ofk-convexn-person games is considered. In casek=n, we are dealing with convexn-person games. Three characterizations ofk-convexn-person games, formulated in terms of the core and certain adapted marginal worth vectors, are given. Further it is shown that fork-convexn-person games the intersection of the (pre)kernel with the core consists of a unique point (namely the nucleolus), but that the (pre)kernel may contain points outside the core. For certain 1-convex and 2-convexn-person games the part of the bargaining set outside the core is even disconnected with the core. The Shapley value of ank-convexn-person game can be expressed in terms of the extreme points of the core and a correction-vector whenever the game satisfies a certain symmetric condition. Finally, theτ-value of ank-convexn-person game is given.     

Raman spectroscopy with an integrated arrayed-waveguide grating

An integrated arrayed-waveguide grating fabricated in silicon-oxynitride technology is applied to Raman spectroscopy. After its validation by reproducing the well-known spectrum of cyclohexane, polarized Raman spectra are measured of extracted human teeth containing localized initial carious lesions. Excellent agreement is obtained between the spectra of healthy and carious tooth enamel measured with our integrated device and spectra recorded using a conventional Raman spectrometer. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers, e.g. for the detection of dental caries at an early stage.     

Novel integrated optic intensity modulator based on mode coupling

The analysis, design, realization, and measurements of a novel intensity modulator are reported. The operating principle is based on mode coupling between a passive low-loss SiON waveguide and an electro-optic high-loss polymer waveguiding structure. Matching the waveguides is critical and results in severe demands for the technology. Extended simulations by the Coupled Mode Theory, the Leaky Wave Model, and Finite Difference Beam Propagation Method resulted in the design of several modulator structures. After realization, modulation could be demonstrated at 632 nm and at 1523 nm using lossy waveguiding modes and surface plasmon modes.