Diethynyl-thiophene adsorbed on Cu(1 0 0) investigated by NEXAFS and XPS

Studies on the chemical stability and interface interaction of diethynyl-thiophene (DET) condensed multilayer at 90 K on Cu(1 0 0) are reported. The temperature influence in the multilayer and monolayer range has been investigated by means of near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the C K-edge. The NEXAFS spectra were recorded at 90 K, 150 K, 200 K, 245 K and 298 K. Comparison with X-ray photoemission spectroscopy (XPS) data, collected on DET at similar temperatures, has also been accomplished. NEXAFS spectra recorded for the multilayer show a strong similarity with those of our previous NEXAFS theoretical and experimental investigations in gas-phase. The multilayer spectra appear affected by the temperature from 90 K to 155 K, while after desorption a broadening of the main π* region occurs, indicative of interaction with the substrate. XPS data at the S2p core level suggests a partial desulphurization reaction that takes place at nearly room temperature with the S–C replaced by a Cu–C bond.