Adsorption structure of NO and CO on Pt

Recently, Matsumoto et al. have analyzed the adsorption structure of NO on Pt(l 1 1) by STM and HREELS on the surface saturated with NO at 70 K and then annealed to 215 K [39], and further by LEED and RAIRS on the three different 2x2 surfaces at low temperatures (90-150 K) [40]. Only molecular NO is desorbed thermally from the Pt(l 1 1) surface with NO saturated at 70 K and three desorption peaks a, (3 and 7 are observed in the thermal desorption spectrum (TDS), as shown in Fig. 7. At low coverages only the a peak in TDS appears at 350 K a new (3 desorption peak at 310 K and a third peak of 7 species at 185 K appear with increasing coverage. However, only one peak of the N-O stretching vibration can be observed in RAIRS [35]. After annealing the NO-saturated surface to 225 K, 

The usual intensity transfer in the infrared absorption /( ) is given by the relation [43] considering the dynamical dipole-dipole coupling relevant to the frequency shift [44], 

Adsorption Site fee Hollow fee Hollow + On-Top fee Hollow + On-Top (On-Top Fixed) fee Hollow + On-Top + hep Hollow 

Only the modes with peak intensities larger than 0.003 are shown. Pt-NO str. 1 and Pt-NO str. 2 represent the Pt-NO stretching modes of the fee hollow and on-top species, respectively. NO rot. represents the frustrated rotational mode of the on-top NO species. The corresponding modes of the hollow NO species have zero intensity because of the upright geometry. N-O str. 1 and N-O str. 2 correspond to the N-O stretching modes of the fee and hep hollow species, respectively, while N-O str. 3 corresponds to that of the on-top species. 

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