Synthesis, structure, and bonding in polyiodide and metal iodide-iodine systems.

Publisher Summary This chapter describes the various aspects of the vibrational spectra of carbohydrates. Vibrational spectroscopy is one of the techniques most adapted techniques for the study of hydrogen bonding, which is the indicator of molecular interaction in the aqueous solutions of sugars. A polyatomic molecule, such as sugar, may be regarded as a system of masses joined by bonds having spring-like properties. The vibration of each of the masses (atoms) can be resolved into components parallel to the x, y, and z axis of a Cartesian system of coordinates. The harmonic approximation is applied in which any motion of the molecule is resolved in a sum of displacements parallel to the Cartesian coordinates and these are called “fundamental, normal modes of vibration.” The analysis of crystallographic results shows the important role played by anomeric center in the structure of sugars. Infrared dichroism in polysaccharides was applied to obtain information on the orientation of chemical groups in the crystalline structure. The computational calculation of the frequencies of carbohydrates' vibration is also elaborated in the chapter.

Vibrational spectra of carbohydrates.

Linear Polyene Electronic Structure and Potential Surfaces

Optical absorption and emission spectra at liquid helium temperatures of solutions of all‐trans‐1,8‐diphenyloctatetraene in single crystals of bibenzyl and polycrystalline n‐paraffin matrixes are presented which show an excited singlet state at a lower energy than the 1Bu state responsible for the strong absorption of all linear polyenes. The transition from the ground state to this level has an oscillator strength of about 0.05. The location of this low energy weak transition removes a number of discrepancies between the expected and observed fluorescence properties of diphenyloctatetraene. The observed vibronic pattern is consistent with the Raman spectrum which is also reported. Substantial indirect evidence is presented which indicates that many, and perhaps all, linear polyenes have a similar ordering of excited states. A review of the available information on diphenylpolyenes is presented. A correlation of the oscillator strength of the fluorescence transition as deduced from the emission lifetime with the separation of the low energy excited states for a number of polyenes is noted. The implications for the photochemistry of linear polyenes including the visual chromophores are pointed out.

Polyene spectroscopy: The lowest energy excited singlet state of diphenyloctatetraene and other linear polyenes

the applicationof this technique in this field has grown exponentially.Although this database and the papers from several groupsthat appeared around the same time introduced many peopleto this research field, these were not the first applications ofRaman microspectroscopy in art analysis. In 1979 Dhamelin-court et al.

M. E. Heyde

Papers

Vibrational spectra of some carotenoids and related linear polyenes. Raman spectroscopic study

Raman spectra of Schiff bases of retinal (models of visual photoreceptors).

Resonance-enhanced Raman spectra of iodine complexes with amylose and poly(vinyl alcohol), and of some iodine-containing trihalides

Raman spectrum of the 11-cis isomer of retinaldehyde.

Raman excitation profiles as probes for inaccessible electronic levels in molecules: Retinal, retinol and naphthalene