Low-energy He + ion scattering spectroscopy (ISS) was performed on the as-deposited samples, and after the sample had been flashed to 750 K. Each ISS experiment comprise a series of ISS spectra, allowing the intensities associated with scattering from Pt, Al, and O atoms in the surface layer to be monitored vs. exposure to the He + beam, which slowly sputters the surface. The Pt ISS intensities plotted below correspond to the average of the peak intensties in the first three spectra measured for each sample. To avoid complications from He + damage to the samples, the as-deposited and post-heating measurements were done on separate, freshly prepared samples.