AVS 56th International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM5
Oxidative Removal of Carbodiimide (NCN) and Isocyanate (NCO) Species from Cu(001) Surfaces

Tuesday, November 10, 2009, 9:20 am, Room N

Session: Reactions on Metals and Bimetallics
Presenter: E.Z. Ciftlikli, Rutgers University
Authors: E.Z. Ciftlikli, Rutgers University
J. Lallo, Rutgers University
E.Y.-M. Lee, Rutgers University
S. Rangan, Rutgers University
L. Tskipuri, Rutgers University
R.A. Bartynski, Rutgers University
B.J. Hinch, Rutgers University
Correspondent: Click to Email
Adsorbed isocyanate (NCO) species on Cu(001) undergoes oxidation, in the presence of O(a), at temperatures as low as 373K. N(a) remains and CO2(g) evolves. On the other hand, a NCO/Cu(001) surface, in the absence of any other coadsorbates, is stable up to ~523K. Above this temperature, a bimolecular decarboxylation reaction is induced, which produces CO2(g) and a surface bound carbodiimide (NCN) species alone. RAIRS measurements confirm a surface parallel species with an “sp” hybridized carbon atom. The introduction of oxygen at room temperature on NCN/Cu(001) leads to the reappearance of NCO species on the surface. The apparent yield of reformed NCO is not simply in proportion to the initial NCO dose levels. The chemistry of the NCO species is affected by the likely coadsorbates; N(a), O(a), and NCN(a). The νa(NCO) bands observed in RAIR spectra of these partially oxidized surfaces, apart from being complex in shape, display a significant blue shift with respect the νa(NCO) modes observed when similar quantities of NCO are adsorbed on coadsorbate-free surfaces. In addition, the annealing of these surfaces to 473K indicates only a partial further oxidation of NCO. Even at excessive O2 doses, NCO is not fully oxidized by 473K. A further annealing to ~ 623K is required for complete NCO removal. We will discuss the possible factors that limit NCO oxidation in these surfaces.