Because CO binds strongly to Pt, CO TPD was used to probe changes in the numbers and strengths of accessible Pt sites under different conditions. Six sequential CO TPD runs were used to probe asprepared Ptn/alumina and PtnGem/alumina samples, with CO dosed at 150K prior to each 3 K/sec heat ramp, and both CO and 13 CO desorption monitored. Fig. shows the results for alumina, Pt4, Pt7, Pt11, Ge/alumina, Pt4Ge, Pt7Ge2, and P11Ge4 samples, and Tables S9-S11 summarize the molecular bookkeeping, using the same calibration approach used for the C2D4 TPD, with estimated ~10% relative and ~50% absolute uncertainties. Values are given for "Total CO/cluster" and for "High T CO", defined as Tdesorption > 335 K for Ptn and 300 K for PtnGem, reflecting the onset of the main high T desorption feature. Significant 12 CO signal was observed only for the 1 st TPD run for Pt4/alumina due to background CO adsorbed during cluster deposition, and for that run, the sum of 12 CO + CO signals is plotted.