Monolayers of medium-chain alcohols CH,(CH,),,-,OH (rn = 9-14) have been studied by sum-frequency vibrational spectroscopy and ellipsometry in the vicinity of the two-dimensional solid-liquid phase transition. Guuche defects are present in the solid phase and increase only slightly in the monolayer just above the phase transition. A model of the chains as freely rotating rigid rods permits a calculation of the area per molecule and chain tilt in the liquid phase. The density of the hydrocarbon chains in the liquid monolayer phase is less than that in the solid monolayer phase but significantly higher than in a bulk liquid alkane. The area per molecule, chain tilt and volume per CH, group in the liquid phase all increase with increasing chain length.

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Sum-frequency (SF) spectra of a monolayer of thiophenol on silver are reported in the mid and far-IR (infrared). The free-electron laser FELIX was used to reach wavelengths up to 54 μm. Molecular vibrations of thiophenol are observed at wavelengths near 10 μm (three modes), 14 μm (1 mode), and 24 μm (1 mode). The appearance of the different vibrational modes in the spectra varies dramatically due to interference between the resonant sum-frequency signal and the nonresonant sum-frequency signal from silver. The standard model used to describe line shapes in SF spectra is shown to be insufficient to explain the different line shapes for the various vibrational modes of thiophenol on silver.

Synthese und Eigenschaften der Carbodiphosphorane [(CH3)2N]3PCP(CH3)[N(CH3)2]2, (3), [(CH3)2N]2(F)PCP(F)[N(CH3)2]2, (7), und (C6H5)2(F)PCP(F)(C6H5) 2, (11), werden beschrieben. Die Verbindungen 3, 7 und 11 sowie [(C2H5)2N]3PC P(CH3)[(C2H5)2N]2 sind durch ihre 1H‐, 13C‐, 19F‐ und 31P‐NMR‐Spektren sowie durch ihre Massenspektren charakterisiert. Die Kristall‐ und Molekülstruktur von 7 werden mitgeteilt.

Devitrification of steam-grown SiO~ films has been studied as a function of time and temperature, with special attention to impurity effects, by monitoring the refractive index of the film and by examining the time, temperature, and imuurity dependent degradation of the dielectric strength. Monitoring of the refractive index showed that partial devitrification may occur in a time scale of weeks at room temperature if the oxide was significantly [~2 (10)15 cm-2] sodium contaminated and had, in addition, a high-temperature (,.~1000~ anneal while contaminated. As-grown slices, for which the sodium contamination level is <1011 cm-2, showed no evidence of devitrification. Electron diffraction observations confirmed the interpretation of the refractive index changes. Dielectric breakdown behavior indicated that the function of the high-temperature anneal was to modify the manner in which the sodium was incorporated into the silica film although nucleation phenomena may also be important. The activation energy for dielectric strength degradation is ~0.1 eV which is much less than the activation energy for devitrification of pure bulk fused silica (2.2 eV). * Electrochemical Society Active Member.