The chemistry of nitro- and amine-substituted aromatic molecules on a
Cu(110) surface has been studied using Fourier transform infrared spec
troscopy, by comparison of the adsorption of nitrobenzene (NB), p-dini
trobenzene (pDNB) and p-nitroaniline (pNA). When nitrobenzene was adso
rbed on a clean Cu(110) surface at room temperature, it decomposed to
form a phenyl species with the C-2 axis nearer the surface normal than
parallel. At 83 K, multilayer nitrobenzene formed with a vibrational
spectrum, in good agreement with gas-phase data; upon warming, a pheny
l species remained, which was stable to about 350 K. AES of the specie
s present following dosing at 300 K showed carbon and oxygen but no ni
trogen. When p-dinitrobenzene was adsorbed it decomposed, losing one N
O2, to form a stable nitrophenyl species on Cu(110) orientated with th
e C, axis closer to the surface normal than the phenyl species derived
from nitrobenzene. In contrast, p-nitroaniline does not decompose on
the Cu(110) surface at room temperature. Multilayer and monolayer p-ni
troaniline are distinguished by frequency shifts of NO2 and NH2 modes,
attributed to intermolecular hydrogen bonding. In the monolayer, the
amine group appears to stabilise the ring-nitro group bond, allowing b
onding to the surface via the NO2 group in an orientation perpendicula
r to the surface.