Angle-resolved X-Ray Photoelectron Spectroscopy Study of the Thiourea Derivative Adsorption on Au(111) from Ethanolic Solution
The adsorption of 1-(2-Furoyl)-3-[3-(trifluoromethyl)phenyl] thiourea on Au(111) from ethanolic solution, was studied by means of angle-resolved X-ray photoelectron spectroscopy (ARXPS). The AR-XPS spectra were obtained at different take-off angles with respect to substrate surface: (50°, 70°, 90° and 110°). The spectra of the C1s at different take-off angles indicated the degradation of the CF3 in CF2 and CF entities. This degradation is due to damages provoked for the effect of the electrons induced by X-ray excitation. High resolution spectra of F1s at these angles, showed two peaks at 687.6 and 688.4 eV, confirming the presence of the organic fluorine (-F-C-) and inorganic fluoride (F-). The X-ray-photoelectron angular measurements were capable of yielding thickness-to-mean free path ratios for the adsorbed layer. Despite of the fluorine lost, such measurements demonstrate the permanence of the CF3 groups in the meta-phenyl position at 10 Å of the inorganic fluoride. A preferential orientation of the species (CFx=1,2,3) at 50° respect to the substrate’s surface was observed.