Infrared Absorption Intensities

Carvone (Problem 12.39) has an intense infrared absorption at 1690 cm-1. What kind of ketone does carvone contain ... 

The catalyst precursor generally used for the reaction is rhodium dicarbonyl acetylacetonate. However, detailed infrared studies under the reaction conditions (ca. 1000 bar CO/H2 and 200°C) have shown both the [Rh(CO)4] and the [Rh12(CO)34 36]2 anions to be present in various concentrations at different stages of the reaction (62, 63). It is suggested that rhodium carbonyl clusters, characterized as having three intense infrared absorptions at 1868 10, 1838 10, and 1785 10 cm-1, are responsible for the catalysis (62), and it is believed that the reaction is dependent upon the existence of the following equilibria ... 

Exercise 9-7 Which compound in each group would have the most intense infrared absorption band corresponding to stretching vibrations of the bonds indicated Give your reasoning. 

Potassium hexafluoroplatinate(IV) may be identified by its x-ray powder diffraction pattern6 and infrared spectrum7 which in a Nujol mull has bands as follows 583(vs), 282(s), 259(ms) cm.-1. The crude product before recrystallization is sufficiently pure for most purposes but preparations carried out in quartz usually contain some potassium hexafluorosilicate, which may be detected by its very intense infrared absorptions at 741 and 483 cm.-1.8... 

Finally, charged excitations on the chain also generate new and intense infrared absorptions (IRAS lines) which are other manifestations of the strength of the electron-phonon coupling. 

Furthermore, it is possible to increase the sensitivity of the IR technique, and thus the probability of detecting transient surface species characterized by (very) low absorption coefficients (such as the intermediate species present during the first steps of the polymerization reaction on the Phillips catalyst) by exploiting the surface-enhanced infrared absorption (SEIRA) effect. It is known that molecules adsorbed on metal island films or particles exhibit 10-1000 times more intense infrared absorption than would be expected from conventional measurements without the metal (253-256). The possibility of performing SEIRA spectroscopy should therefore be expected to provide an opportunity to better investigate the nature of the intermediate species, not only for ethene polymerization on Cr(II)/ Si02, but for other reactions on solid catalysts. 

SIERA Surface-enhanced infrared absorption As in the case of surface-enhanced Raman scattering (SERS), molecules adsorbed on metal island films or particles exhibit intense infrared absorption several folds higher than what one would expect from conventional measurements without the metal. This effect is referred to as surface-enhanced infrared absorption (SEIRA). 

Raman scattered intensity infrared absorption Bessel functions light velocity... 

The characteristic intense infrared absorption bands in these types of complexes can be divided into five frequency ranges a C—H stretching frequency at 3010-3060 cm" a C—C stretching frequency at 1410-1430 cm" ... 

Isolation of the sample compartment from the outside air is very important. Water vapor and carbon dioxide in the air exhibit intense infrared absorptions and it is usually difficult to... 

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