Identification of reconstruction in Pt films deposited on Pd(110) at room temperature

We have studied the properties of Pt films on Pd(110), grown by deposition at 300 K and annealed up to 900 K, using low-energy electron diffraction and Auger-electron spectroscopy. We observe (1×{}2) and (1×{}3) superstructures, depending upon Pt coverage and annealing temperature. At one monolayer, the (1×{}1) periodicity is unperturbed. Between one and three monolayers, a broad and streaky (1×{}2) develops upon annealing, then fades to (1×{}1) as the film dissolves. At three monolayers and above, the broad and streaky (1×{}2) splits to a (1×{}3), then fades again to (1×{}1) at high temperature. Adsorption of CO causes (1×{}3){→}(1×{}1) reversion at relatively low temperature, 430 K. Based upon the known behavior of Pt(110) reconstructions, this is strong evidence that the (1×{}3) structure of the Pt film is a surface reconstruction.