Isolation and thermal reactions of the intermediates from BrCH ₂CH₂OH decomposition on Cu(100) and oxygen-precovered Cu(100)

The reactions of BrCH₂CH₂OH were investigated on clean and oxygen-precovered Cu(100) surfaces under ultrahigh vacuum conditions. Reflection-absorption infrared spectroscopy (RAIRS) studies were performed to examine the surface intermediates that were generated from BrCH ₂CH₂OH decomposition. Density functional theory calculations were employed to predict the infrared spectra, assisting in the identification of the reaction intermediates. On Cu(100), -CH₂CH ₂O-, formed from the simultaneous scission of the bromine-carbon and oxygen-hydrogen bonds of BrCH₂CH₂OH at ∼190 K, decomposed and evolved into C₂H₄ between 210 and 310 K in temperature-programmed reaction/desorption (TPR/D) experiments. A small amount of CH₃CHO desorption was also observed. On oxygen-precovered Cu(100), -CH₂CH₂O- was also generated at lower exposures (<1.5 L) but at the BrCH₂CH₂OH dosing temperature of 115 K. The TPR/D study showed that C₂H₄ with minor amounts of CH ₃CHO evolved between 210 and 310 K. However, at higher BrCH ₂CH₂OH exposures (≥1.5 L), BrCH₂CH ₂O- was the major intermediate formed at ∼200 K. The formation temperature of C₂H₄ and CH₃CHO was extended to ∼400 K in this case.