Thermal Decomposition of Octanethiolate Self-Assembled Monolayers on Cu(111) in UHV

Abstract
Octanethiol (CH3(CH2)7SH) based self-assembled monolayer on Cu(111) in ultra-high vacuum has been examined using x-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), intergrated desorption mass spectrometry (IDMS), and contact angle analysis. The results show that the octanethiolate monolayers similar to those on gold are formed on Cu(111). The monolayers are stable up to temperatures of about 480 K. Above 495 K the monolayers decompose via the γ-hydrogen elimination mechanism to yield 1-octene in the gas phase. The thiolate head groups on the copper surface change to Cu 2S following the decomposition of hydrocarbon fragments in the monolayers at about 605 K.