CRISTINA lucila Josefina
Growth of 1,4-Benzenedimethanethiol Films on Au, Ag, and Cu: Effect of Surface Temperature on the Adsorption Kinetics and on the Single versus Multilayer Formation
LEONARDO SALAZAR ALARCÓN; LUCILA J. CRISTINA; JIE SHEN; JUANJUAN JIA; VLADIMIR A. ESAULOV; ESTEBAN A. SÁNCHEZ; OSCAR GRIZZI
JOURNAL OF PHYSICAL CHEMISTRY C
AMER CHEMICAL SOC
Lugar: Washington; Año: 2013 vol. 117 p. 17521 - 17530
We report a study of 1,4-benzenedimethanethiol (BDMT)adsorption on the (111) surface of the noble metals Au, Ag, and Cu performedfrom the vapor phase by ion scattering. The better known case of BDMT on theAu(111) surface is used for comparison. Ion scattering carried out in the forwarddirection to detect both scattering and recoiling atoms allowed us to delineate thetwo main different film configurations: with both S atoms attached to the surfaceand with S exposed at the vacuum interface. The experiments were carried out atroom temperature (RT) and around 250 K. At RT we found that a monolayer ofstanding-up molecules can be formed on all of the surfaces at very high exposures,that is, approaching the Mega Langmuir for Au and Ag. Comparison withexperiments of adsorption of S2 on the Au(111) bare surface allowed us to estimate that the S content at the BDMT−vacuum interface is ∼0.3 of a monolayer. The adsorption at lower temperatures has two main effects: it enhances the sticking coefficient and results in the formation of a multilayer at lower exposures. The discrimination of the monoversus the multilayer film formation with the ion scattering technique is discussed. Once the multilayer is formed, the increase of the surface temperature to 270 K is sufficient to obtain a monolayer with spectral features that are similar to those obtained at RT with much higher exposures.