Enhanced Raman Scattering from Molecules Adsorbed on Small Nickel Particles

Abstract

We have investigated the Raman enhancement of simple molecules like benzene, coadsorbed benzene and hydrogen, carbon monoxide, ethylene, coadsorbed carbon monoxide and hydrogen, which are bonded to the surfacé of small nickel particles. The enhancement depends strongly on the structure and diameter of the particles and on the excitation wavelength. The maximum of the enhancement is generally observed in the wavelength range of 5200 Å – 4500 Å and is about 10³ –10⁴ compared with those wavelengths, where no enhancement could be measured. If there exist several surface species or if chemical reactions take place on the surface, the spectra of all chemisorbed molecules are enhanced in the same way.