Haruka Yamada

Ultraviolet excitation of Raman spectra of pyridines adsorbed on oxides

The Raman spectra of pyridines adsorbed on silicas, silica–alumina and γ-alumina have been measured with an ultraviolet excitation (363.8 nm). The Raman intensities are considerably enhanced by the u.v. excitation for some adsorbed species. The Raman bands assigned to the species on Bronsted and Lewis acid sites have been observed even on silicas pretreated at 500°C.

Resonance Raman spectra of carbonium ions adsorbed on porous Vycor glass

Measurements of Raman spectra for unstable intermediates adsorbed on porous Vycor glass (PVG) have been made. When 1,1-diphenylethylene (DPE) was adsorbed on PVG, some unstable intermediates, blue, green and yellow species, were produced. Resonance Raman spectra of the green and yellow samples were obtained. The green species showed three new bands at 2975, 2930 and 2873 cm–1 and the yellow species one at 2930 cm–1. The observed Raman spectra confirm the existence of two kinds of carbonium ions. The structure of the carbonium ions and the formation mechanism of the intermediates were considered. Applicability of this technique to the study of small quantities of surface species is discussed.

Infrared Spectra of Crystalline CHCl 3 and CDCl 3

The infrared spectra for the fundamental absorption bands, ν1, ν2, ν4 and ν5, of CHCl3 and CDCl3 have been measured in polycrystalline films. For the C–H or C–D bending band a triplet has been observed in the pure crystal. The spectra of a mixed crystal (CHCl3: CDCl3) have also been studied over the entire concentration range. The space group of crystalline chloroform has been determined to be D2h16. The intensity of the band changes, going from the gas to the solid, depending on the symmetry species to which the vibrational mode belongs; the A1 bands increase in intensity, while the E bands decrease. The C–H stretching band shows an especially remarkable increase.