Phenol adsorption on ZnO (0001) probed by coherent anti-stokes Raman scattering spectroscopy using guided waves

Abstract

Adsorption of phenol on a well defined (0001) surface of ZnO has been investigated with coherent anti-Stokes Raman scattering spectroscopy (CARS) using planar optical waveguide geometry. Monolayer sensitivity was achieved by establishing an interference condition within the ZnO layer to minimize the CARS signal from the film. At relatively higher surface coverages both physisorbed and chemisorbed phenol were present on the surface; however, with continuous pumping of the vacuum chamber all the physisorbed species were removed from the surface. The chemisorbed species is retained as the phenoxide on ZnO (0001) surface.