Kim C S, Korzeniewski C
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061.
Anal Chem. 1997 Jul 1;69(13):2349-53. doi: 10.1021/ac961306k.
Adsorption of carbon monoxide at step and terrace sites on a Pt(557) ≡ Pt(s)-[6(111) × (100)] electrode was detected with infrared spectroscopy. Vibrational coupling between adsorbates provided insights into the assembly of molecules at the different structural sites. The intermolecular coupling was weak at low coverages as CO ordered along the steps. For coverages between 40 and 70% of saturation, separate bands assignable to CO on steps and CO on terraces appeared. Coupling across this coverage range was markedly weaker on Pt(557) than on the structurally related Pt(335) ≡ Pt(s)-[4(111) × (100)] electrode surface. The results indicate that, after the steps fill, CO populates the terraces on Pt(557) at random rather than by ordering in alignment with the steps. At coverages below saturation, vibrational bands assignable to CO molecules at step and terrace sites are affected differently by changes in electrode potential. The potential-induced spectral changes for the terrace CO bands are similar to those of Pt(111)/CO, but the step CO bands show deviations from this trend at hydrogen adsorption potentials.
利用红外光谱法检测了一氧化碳在Pt(557)≡Pt(s)-[6(111)×(100)]电极的台阶和平台位置上的吸附情况。吸附质之间的振动耦合为不同结构位置上分子的组装提供了见解。在低覆盖度下，由于一氧化碳沿台阶有序排列，分子间耦合较弱。对于饱和度在40%至70%之间的覆盖度，出现了可归因于台阶上的一氧化碳和平台上的一氧化碳的单独谱带。在这个覆盖度范围内，Pt(557)上的耦合明显比结构相关的Pt(335)≡Pt(s)-[4(111)×(100)]电极表面上的耦合弱。结果表明，在台阶填满后，一氧化碳在Pt(557)的平台上随机分布，而不是与台阶对齐有序排列。在低于饱和度的覆盖度下，可归因于台阶和平台位置上一氧化碳分子的振动谱带受电极电位变化的影响不同。平台一氧化碳谱带的电位诱导光谱变化与Pt(111)/CO的相似，但台阶一氧化碳谱带在氢吸附电位下偏离了这一趋势。
