Using the method of time-domain spectroscopy, we measure the far-infrared absorption and dispersion from 0.2 to 2 THz of the crystalline dielectrics sapphire and quartz, fused silica, and the semiconductors silicon, gallium arsenide, and germanium. For sapphire and quartz, the measured absorptions are consistent with the earlier work below 0.5 THz. Above 1 THz we measure significantly more absorption for sapphire, while for quartz our values are in reasonable agreement with those of the previous work. Our results on high-purity fused silica are consistent with those on the most transparent fused silica measured to date. For the semiconductors, we show that many of the previous measurements on silicon were dominated by the effects of carriers due to impurities. For high-resistivity, 10-kΩ cm silicon, we measure a remarkable transparency together with an exceptionally nondispersive index of refraction. For GaAs our measurements extend the precision of the previous work, and we resolve two weak absorption features at 0.4 and 0.7 THz. Our measurements on germanium demonstrate the dominant role of intrinsic carriers; the measured absorption and dispersion are well fitted by the simple Drude theory.

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Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors

In this review the phenomenon of proton conductivity in materials and the elements of proton conduction mechanismsproton transfer, structural reorganization and diffusional motion of extended moietiesare discussed with special emphasis on proton chemistry. This is characterized by a strong proton localization within the valence electron density of electronegative species (e.g., oxygen, nitrogen) and self-localization effects due to solvent interactions which allows for significant proton diffusivities only when assisted by the dynamics of the proton environment in Grotthuss and vehicle type mechanisms. In systems with high proton density, proton/proton interactions lead to proton ordering below first-order phase transition rather than to coherent proton transfers along extended hydrogen-bond chains as is frequently suggested in textbooks of physical chemistry. There is no indication for significant proton tunneling in fast proton conduction phenomena for which almost barrierless proton transfer is suggest...

Proton Conductivity: Materials and Applications

Organic molecules as well as metal complexes may exist as several geometric isomers1 which display distinct physical properties and chemical reactivities. A molecule containing two atoms (in general, two carbons) attached together by a double bond with substituents W-Z may be found as two isomeric † C.D. dedicates this review to Professor Andrée Marquet as a mark of his admiration and gratitude. * To whom correspondence should be addressed: Tel: (33) 169 08 52 25. Fax: (33) 169 08 90 71. E-mail: christophe.dugave@cea.fr. ‡ Present address: Département de Chimie, Institut de Pharmacologie, Université de Sherbrooke, 3001, 12e Avenue nord, Sherbrooke, Québec, J1H 5N4 Canada. 2475 Chem. Rev. 2003, 103, 2475−2532

Cis-trans isomerization of organic molecules and biomolecules: implications and applications.

http://www.sciencemadness.org/talk/files.php?pid=96085&aid=3127

Production of succinic acid by bacterial fermentation

Introductory Fourier transform spectroscopy

Far‐infrared absorption coefficients of silicon crystals grown by the Czochralski method (CZ) and by the floating‐zone method (FZ) in the range of 20–200 cm−1 were obtained from transmission measurements at two different thicknesses, allowing for the effect of the multiple internal reflection. The CZ and FZ specimens used were not intentionally doped and had dc resistivities of 9.4±0.3 Ω cm and (5±2)×104 Ω cm, respectively. The impurity‐induced absorption of the CZ crystal is well explained by the Drude model, while the FZ crystal showed only a weak absorption which is attributed to a wing of the intrinsic lattice band of silicon.

Far‐infrared absorption of silicon crystals

Far-infrared absorption spectra of liquid acetonitrile at temperatures ranging from 238 to 343 K were measured with a source of synchrotron orbital radiation. On the basis of an optical theory, a theoretical expression for transmittance of a cell filled with liquid was obtained as a function of the optical constants of the liquid. Assuming an analytical form with seven parameters for the absorption coefficients, the refractive indices were analytically calculated by the Kramers-Kronig relation. The parameters of the absorption coefficients were adjusted by least-squares fitting of the theoretical transmittance to the observed transmittance. The resulting optical constants at 298 K were in good agreement with the previously reported results by a laser ATR method. The effect of temperature on the band shape of the absorption is remarkable and will provide an important clue to molecular reorientational dynamics. On the other hand, the molecular dipole moments obtained from the integrated intensities are near...

Far-infrared optical constants of liquid acetonitrile at 238 to 343 K as measured with a synchrotron radiation source

Infrared and molecular dynamics study of reorientational relaxation of liquid acetonitrile

Near-infrared absorption of the OH stretching overtone transition of water has been measured at temperatures and pressures in the ranges of 373–673 K and 20–400 bar, respectively. The absorption profile at 673 K and 400 bar retains a mark of rotational structure, indicating that an appreciable proportion of water molecules can rotate quite freely. The molar absorption intensity decreases linearly with increasing pressure in the low-pressure region. Enthalpy for dimerization has been estimated to be 15±3 kJ/mol from the temperature dependence of the slopes. Plots of the molar absorption intensity against molar concentration are observed to be located on a single curve irrespective of the temperature. This fact indicates that the ratio of hydrogen-bond formation is largely dependent on the molar density only. A good correlation between the molar absorption intensity and the first moments of the band has been found out; this will be useful in the study of aqueous mixtures.

https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/1396/1/JCP119-23.pdf

Shun-ichi Ikawa

Papers

Far‐infrared absorption of silicon crystals

Far-infrared optical constants of liquid acetonitrile at 238 to 343 K as measured with a synchrotron radiation source

Infrared and molecular dynamics study of reorientational relaxation of liquid acetonitrile

Near-infrared spectroscopic study of water at high temperatures and pressures

Vibrational spectra and conformation of polyethylene glycol complexed with calcium and magnesium chlorides