Adsorbate-Substrate Interaction: A Raman Study of Pyridine Adsorbed on γ-Al₂O₃ at Very Low Coverages

Metal−Metal Bonding and Structures of Metal String Complexes Cr3(dpa)4Cl2, Cr3(dpa)4(NCS)2, and [Cr3(dpa)4Cl2](PF6) from IR, Raman, and Surface-Enhanced Raman Spectra

“…34,35 The spectral intensities of lines, for example, at 363, 424, 668, 1057, 1311, and 1429 cm -1 assigned to vibrational modes with a symmetry, are relatively enhanced. According to the surface selection rules for Raman intensity, 36 modes with a Wilson notation for vibrational modes of pyridyl is used. Symbols are defined in Figure 1.…”

Surface Acidity and Properties of TiO2/SiO2 Catalysts Prepared by Atomic Layer Deposition: UV−visible Diffuse Reflectance, DRIFTS, and Visible Raman Spectroscopy Studies

“…Little attention has been paid to other vibrational modes such as ν 6b and ν 9a , two in-plane C-H bending modes, for the study of acidity, especially Brønsted acid sites. 47 Solution phase Raman spectra of pyridine ( Figure 7) exhibit bands throughout the 500-3200 cm -1 range. The most intense vibrational modes are ν 1 , ν 12 , and ν 2 .…”

“…Compared with IR spectroscopy, 13,14,[17][18][19]42,43 Raman spectroscopy has rarely been applied to study the acidity of catalysts using pyridine as a probe molecule. [45][46][47][48][49] Raman spectroscopy is sensitive to adsorption on Lewis acid sites and to species adsorbed by H-bond interactions, but bands characteristic of adsorption on Brønsted acid sites have been difficult to identify. 46,47 Sample fluorescence is also often a problem.…”

“…[45][46][47][48][49] Raman spectroscopy is sensitive to adsorption on Lewis acid sites and to species adsorbed by H-bond interactions, but bands characteristic of adsorption on Brønsted acid sites have been difficult to identify. 46,47 Sample fluorescence is also often a problem. To the best of our knowledge, Hendra was the first to apply Raman spectroscopy in studies of surface acidity using adsorbed pyridine on oxide surfaces.…”

Nature and Estimation of Functional Groups on Solid Surfaces

“…The use of "multiplex" (position sensitive) detection where the spectral information of the entire spectral range is available simultaneously at the multichannel detector, improves the instrument sensitivity considerably (> x 1000) over that of conventional scanning instruments [295]. The value of this increased optical efficiency was demonstrated by Freemann et al [295] and by Heaviside et al [296], when they studied the adsorption of pyridine on y-AI 2 0 3 • Figure 23 compares the Raman spectra of chemisorbed pyridine on y-AI 2 0 3 , which were recorded with photon counting (PC) and multiplex detection by means of an optical multichannel analyzer (OMA). It is clearly evident from this comparison, that multiplex detection yields significantly higher SIN ratios at considerably lower data accumulation times.…”