SFG spectroscopy from 10−8 to 1000 mbar: less-ordered CO structures and coadsorption on Pd(1 1 1)

Vibrational sum frequency generation spectroscopy was employed to study “less-ordered” phases resulting from low-temperature CO exposure on Pd(1 1 1). Such imperfect structures may also occur under catalytic reaction conditions up to 1000 mbar and originate from the superposition of ordered structures when the CO mobility and flux were insufficient. The effect of coadsorbed hydrogen and water was also examined.