Accession Number : ADA189741

Title :   The Reactions of C2H2 and CH3C2H on Ag Powder.

Descriptive Note : Technical rept.,

Corporate Author : AMHERST COLL MA DEPT OF CHEMISTRY

Personal Author(s) : Dorain, Paul B ; Boggio, Joseph E

PDF Url : ADA189741

Report Date : 10 Dec 1987

Pagination or Media Count : 10

Abstract : Ag powder is activated by pulsing it with NO2 gas which forms fresh Ag microclusters. This powder is then exposed to subsequent pulses of C2H2 or CH3C2H (3.7% in N2). The surface enhanced Raman Scattering (SERS) spectra show dramatic intensity variations due to rapid changes in adatom concentration. Normalization of these time-dependent SERS spectra to the background scattering intensity, which is proportional to the adatom concentration, provides spectra which represent adsorbate coverage if major surface reconstruction does not occur. The temporal development of the SERS spectra of C2H2 shows rapid degradation with no evidence for adsorbed species. In contrast, propyne reacts more slowly, as evidenced by the behavior of the intensity at 1980/cm due to adsorbed -C2-. The reactions observed are in accord with the models developed by Barteau and Madix and Vohs, Carney, and Barteau. Exposure to both alkynes results in the appearance of SERS active NO, and adsorbant not previously observed at room temperature. Keywords: Surface enhanced raman scattering, Acetylene, Propyne, Ellipsometry, Catalysis, Silver.

Descriptors :   *ACETYLENE, *ALKYNES, *CATALYSIS, *ELLIPSOMETERS, *SILVER, ADSORPTION, BACKGROUND, DEGRADATION, INTENSITY, LIGHT SCATTERING, RAMAN SPECTRA, ROOM TEMPERATURE, SCATTERING, VARIATIONS

Subject Categories : Organic Chemistry
      Inorganic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE