DTIC ADA069734: Infrared Spectroscopic Study of Activated pdf

DTIC ADA069734: Infrared Spectroscopic Study of Activated

More Book Details

Description of the Book:

The infrared spectrum of CO chemisorbed on alumina-supported Rh surfaces has been studied following chemisorption at cryogenic temperatures. Major differences are observed in the distribution and spectroscopic character of chemisorbed CO species produced at low temperatures (110-170K) compared to chemisorbed CO species produced on Rh at 295 K. It has been found that the species rh(CO)2, formed on isolated Rh sites, is produced rapidly via an activated chemisorption process above about 200 K. On more ‘crystalline’ Rh(x) sites, containing chemisorbed CO, an activated CO-adsorbate-conversion process has been detected in which nu sub CO decreases by about 50/cm on warming the adsorbed layer above approx. 265 K. Isotopic exchange between about 13CO(g) and 12CO(ads) been shown to occur rapidly at low temperature (approx. 200k) for Rh(CO)2 species, whereas Rh(x)(CO) species exchange rapidly only at higher temperatures (somewhat 250 K). These results, taken together, serve to confirm a model in which isolated Rh sites coexist on the alumina support with crystalline Rh (x) sites; the two kinds of sites are separable on the basis of the spectroscopic character of the chemisorbed CO species they adsorb as well as by means of their chemical properties.

(Author

• Creator/s: Defense Technical Information Center
• Date: 4/1/1979
• Year: 1979
• Book Topics/Themes: DTIC Archive, Yates, John T, Jr, NATIONAL BUREAU OF STANDARDS WASHINGTON DC SURFACE SCIENCE DIV, *CARBON MONOXIDE, *CHEMISORPTION, *RHODIUM, THERMAL PROPERTIES, INFRARED SPECTROSCOPY, MOLECULAR VIBRATION, CRYOGENICS, INFRARED SPECTRA, ISOTOPE EXCHANGE

An excerpt captured from the PDF book