Angle-resolved X-Ray Photoelectron Spectroscopy Study of the Thiourea Derivative Adsorption on Au(111) from Ethanolic Solution

M. P. Hernández; G. Navarro-Marín; O. Estévez-Hernández; M. H. Farías-Sánchez

M. P. Hernández Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Plaza de la Revolución, La Habana 10400, Cuba
G. Navarro-Marín Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Plaza de la Revolución, La Habana 10400, Cuba
O. Estévez-Hernández Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Plaza de la Revolución, La Habana 10400, Cuba
M. H. Farías-Sánchez Centro de Nanociencias y Nanotecnología (CNyN), Universidad de Nacional Autónoma de México (UNAM), km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860, México

Abstract

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 (CF_x=1,2,3) at 50° respect to the substrate’s surface was observed.