INVESTIGADORES
BERDAKIN Matias
congresos y reuniones científicas
Título:
Thermal Stability of Alkanethiolate Monolayers Investigated by Electrochemical Detection of Thermal Decomposition Products
Autor/es:
F.P. COMETTO; C.A. CALDERON; M. BERDAKIN; D.K. JACQUELINE; V.A. MACAGNO; E.M. PATRITO
Lugar:
Niza
Reunión:
Congreso; 61st Annual Meeting of the Internacional Society of Electrochemistry; 2010
Institución organizadora:
International Society of Electrochemistry
Resumen:
The aim of this work is to show that the thermal stability of alkanethiol monolayers on gold can be studied out of UHV conditions in a N2 atmosphere and that the sulfur-containing thermal desorption products can be monitored with high sensitivity by means of electrochemical reductive desorption experiments. We show that the thermal behavior of the monolayer in this inert atmosphere is in very good agreement with that observed under UHV conditions. To the best of our knowledge, this is the first work that determines desorption temperatures and activation energies by electrochemical methods. The self assembled monolayer was formed on Au(111) by the immersion method and it was then transferred to a N2 atmosphere where it was heated at different temperatures. After a given heating time, the sample was transferred to the electrochemical cell and it was examined at 298 K by means of AC impedance spectroscopy and reductive desorption experiments. The latter technique allowed to accurately monitor the sulfur content of the surface either as alkanethiolate or as atomic sulfur. The desorption temperature and the activation energy barrier for desorption could be obtained with this methodology without the need for ultra high vacuum conditions. As a prototype alkanethiol, we used 1-hexadecanethiol (C16T). The C16T monolayer was stable and defect free up to 130ºC. The decomposition of the SAM at higher temperatures first involved the desorption of 80 % of the monolayer and then the breakage of the S-C bond giving rise to atomic sulfur on the surface. At 190ºC there was no evidence of adsorbed C16T molecules. A desorption temperature of 161ºC and an activation energy barrier of 35 kcal mol-1 were obtained in good agreement with previous works performed under UHV conditions.