against the existence of a "universal isotherm" where the value of d(N2) would be independent of the nature of the surface. On the other hand, it is certainly possible to construct a "family isotherm". Unfortunately, for surface area determination there remains the problem of the value of d(N2) in the first adsorbed layer, which cannot be predicted from the shape of the isotherm.Acknowledgment. This paper reports on part of a project supported by the "Fonds National Suisse de la Recherche Scientifique". We acknowledge the help of Dr.Ph. Schneider in synthetic work and a gift of Dynazirkon F from Dynamit Nobel Chemicals (Troisdorf, FRG). We are thankful for discussions with Dr. A. T. Liu from Degussa Research (Hanau, FRG).

Plasmonic surfaces have emerged as a powerful platform for biomolecular sensing applications and can be designed to optimize the plasmonic resonance for probing molecular vibrations at utmost sensitivity. Here, we present a facile procedure to generate metallic microdisc antenna arrays that are employed in surface-enhanced infrared absorption (SEIRA) spectroscopy of biomolecules. Transmission electron microscopy (TEM) grids are used as shadow mask deployed during physical vapor deposition of gold. The resulting disc-shaped antennas exhibit enhancement factors of the vibrational bands of 4 × 10 giving rise to a detection limit <1 femtomol (10 mol) of molecules. Surface-bound monolayers of 4-mercaptobenzoic acid show polyelectrolyte behavior when titrated with cations in the aqueous medium. Conformational rigidity of the self-assembled monolayer is validated by density functional theory calculations. The membrane protein sensory rhodopsin II is tethered to the disc antenna arrays and is fully functional as inferred from the light-induced SEIRA difference spectra. As an advance to previous studies, the accessible frequency range is improved and extended into the fingerprint region.

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We measured cathodoluminescence (CL) spectra of SiO2 films grown on 4H-SiC wafers and found that for an acceleration voltage of 5 kV, CL peaks at 460 and 490 nm, assigned to oxygen vacancy centers (OVCs), become weak by post-oxidation annealing in N2O ambient at 1300 °C whereas the CL peak around 580 nm, related to Si-N bonding structures, becomes intense. Furthermore, the peak assigned to N-Si3 configurations in x-ray photoelectron spectroscopy (XPS) spectra was observed in the SiO2/SiC interface in only samples annealed in N2O ambient. These results suggest that the interface trap densities decrease and the channel mobility in n-type MOS capacitors increases by the termination of dangling bonds by the N atom in the SiO2/SiC interface. CL spectroscopy and XPS provide us with extensive information on OVCs and dangling bonds in the SiO2/SiC interface on the 4H-SiC substrate.