Adsorbed CO chain condensation and evaporation on Pt{110}-(1×2) at 30–70 K studied by RAIRS

At very low CO coverages on Pt{110}-(1×2) at 30 K, two C–O stretch infrared bands are observed. Warming to >40 K results in the loss of the high-frequency band and growth of the low-frequency band. Further warming to ⩾60 K reverses this process. This reversal is attributed to a thermodynamic transition between 1D islands, or chains, of CO molecules and a 1D gas. The process at ⩾40 K is attributed to the onset of surface diffusion, when chain condensation occurs from the adsorbate randomly formed at 30 K.