A. Enders

Photonic Tunneling Experiments: Superluminal Tunneling

We report on microwave experiments with evanescent modes. The propagation of these “tunneling” modes appear to be instantaneous inside the barrier region independent of barrier length. Data were obtained from various potential barrier configurations and with two basically different measuring procedures. All the results point to a superluminal propagation of evanescent modes through opaque barriers. We question the analogy between evanescent mode propagation and quantum mechanical tunneling.

Hydration dependence of molecular mobility in phospholipid bilayers

Abstract Dielectric measurements on di-myristoil-phosphatidylcholine (DMPC)—water bilayers at different water contents up to 0.50 w/w (dry basis) corresponding to approximately 18 mol of water per mol of DMPC by means of the thermally stimulated depolarization currents (TSDC) method in the temperature range 77–320 K show three broad peaks. For fully hydrated samples the peaks are at about 140, 210 and 230 K. Using special peak resolving thermal sampling and partial heating techniques the complex thermograms were analyzed and the spectra of activation energies were determined. In the order of increasing temperature the peaks were attributed to the relaxation of loosely bound water molecules, the rotation of the head groups and, tentatively, space charge polarization. The measurements show that water in excess of 0.08 corresponding to 3 mol of water per mol of DMPC forms clusters, in agreement with the results of water adsorption isotherms measurements.

On the conductivity of mesoscopic metals and semiconductor structures: device aspects

Abstract Small metals have a size-reduced electrical conductivity. This property allows the preparation of high loss dielectrics with a metal-like dispersion. These novel dielectrics are useful for various applications in radiofrequency and microwave technology. In narrow semiconductor structures the wave nature may dominate over the particle character in electron transport. Two such examples are introduced and the design of devices based on the wave nature of the electron are proposed.

Dynamic properties of phospholipid-water multilayers studied by dielectric relaxation spectroscopy

The authors report on thermally stimulated depolarization currents (TSDC) measurements in the temperature range 77-320 K on hydrated di-myristoil-phosphatidylcholine at different water contents up to 0.33 w/w, corresponding to approximately 18 water molecules per lipid molecule. The different relaxation mechanisms contributing to the complex thermograms are analyzed using special TSDC techniques, and the corresponding spectra of activation energies and entropy factors are determined. The results are discussed in terms of different structures of water in the context of multiphase model and head group mobilities.<<ETX>>

A Novel Class of Dielectrics for Microwave and High-Frequency Applications

Metal-particles of the submicrometer size range are embedded in conventional dielectric materials. The resulting electromagnetic behavior of such a hetero-structured dielectric shows novel properties which are of fundamental importance both for basic physics research and technical applications. Here we report on the presently available dielectric parameters. Depending on the metal particle size, its volume filing factor and the preparation procedure, the complex dielectric function can be taylored for the respective demands: dielectric loss, frequency dependence, temperature dependence as well as additional mechanical and thermal properties can be adjusted in a range having never been achievable before.