LASER-INDUCED THERMAL DECAY OF PYRIDINE AND CHLORIDE SURFACE-ENHANCED RAMAN SCATTERING AS A PROBE OF SILVER SURFACE-ACTIVE SITES

• Main Author: Sobocinski, Raymond Louis, 1962-
• Language: en_US
• Published: The University of Arizona. 1987
• Subjects: Electrochemistry.; Surface chemistry.; Pyridine > Thermal properties.; Chlorides > Thermal properties.; Silver > Thermal properties.
• Online Access: http://hdl.handle.net/10150/276553

The activation parameters for the temperature dependent irreversible loss of surface-enhanced Raman scattered (SERS) intensity from pyridine and chloride adsorbed at silver surfaces in an electrochemical environment have been determined. Laser-induced heating is introduced as a probe of the chemical nature of SERS-active sites. Surface temperatures are calculated from spectroscopic data. The activation energies associated with the destruction of SERS-active sites at a surface roughened by an illuminated oxidation-reduction cycle (ORC) are 12.8 ± 3.2 kcal/mole and 27.7 ± 3.1 kcal/mole for pyridine at two different types of sites on the Ag surface. Similarly, values for coadsorbed chloride are found to be 11.1 ± 2.4 kcal/mole and 24.5 ± 3.8 kcal/mole. An activation energy of 27.4 ± 1.9 kcal/mole is obtained for pyridine on a silver surface roughened by a nonilluminated ORC. Evidence for the desorption of pyridine and chloride is presented.