The bonding of aldehydes on aluminium: benzaldehyde on Al(111)

The adsorption of benzaldehyde on Al(111) at 90 and 300 K has been investigated using ARUPS, HREELS and work-function measurements. Benzaldehyde adsorbs readily at both temperatures, with monolayer saturation reached at an exposure of 1.4 L. Bonding occurs via the aldehyde functional group rather than the ring π electrons. At 90 K, the functional group remains intact, while at 300 K, the CO bond breaks, forming direct covalent bonds to the metal surface. At 90 K, the molecule lies flat, while at 300 K, the ring tilt depends on coverage, with the saturated monolayer containing considerably more material than at 90 K.