ADSORPTION OF NITROBENZENE AND SOME SIMPLE DERIVATIVES ON THE CU(110)SURFACE

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.