Rf-GDOES depth profiling analysis of a monolayer of thiourea adsorbed on copper

The first example of depth profiling analysis, by rf-GDOES, of a layer of sub-nanometre thickness is presented. The example selected is that of a monolayer of thiourea adsorbed on a mirror-polished copper substrate. The adsorbed layer is disclosed clearly in the depth profile as narrow peaks, above the copper substrate, of carbon, hydrogen, nitrogen and sulfur. Further, the positions of peaks are separated and located in the order that is expected from the orientation of the thiourea molecules adsorbed on the copper substrate, namely the nitrogen peak was observed prior to the sulfur peak