IR chemiluminescence probe of the vibrational energy distribution of CO₂ formed during steady-state CO oxidation on Pt(111) and Pt(110) surfaces

The infrared (IR) chemiluminescence spectra of CO₂ were measured during the steady-state CO + O₂ reaction over Pt(110) and Pt(111) surfaces. Analysis of the IR emission spectra indicates that the bending vibrational temperature (Tv^B), as well as the antisymmetric vibrational temperature (Tv^AS), was higher on Pt(110) than on Pt(111). On the Pt(110) surface, the highly excited bending vibrational mode compared to the antisymmetric vibrational mode was observed under reaction conditions at low CO coverage (θ_co < 0.2) or at high surface temperatures (T_s ≥ 700 K). This can be related to the activated complex of CO₂ formation in a more bent form on the inclined (111) terraces of the Pt(110)(1 × 2) structure. On the other hand, at high CO coverage (θ_coco > 0.2) or at low surface temperatures (T_s < 650 K), T_v^AS was higher than T_v^B, which can be caused by the reconstruction of the Pt(110)(1 × 2) surface to the (1 × 1) form with high CO coverage.