Ptn/alumina samples were prepared by depositing mass-selected Ptn + on the alumina support at an energy 1 eV/atom, monitoring and controlling the deposition via the neutralization current. All samples contained the same total number of Pt atoms (equivalent to 10% of a close-packed Pt monolayer), differing only in the size of clusters deposited. To minimize adventitious adsorption on the samples during the initial sample holder cool-down process, the alumina films were briefly flashed to 750 K, and cluster deposition was started as the sample cooled below 300 K. TPD or other experimental steps were then carried out immediately after deposition was completed.