Spin Trapping of Molecules Adsorbed on Zinc Oxide

The reactions of the spin trap PBN with hydrogen and propylene adsorbed on ZnO are reported. For hydrogen, evidence is presented that the species trapped are H atoms adsorbed on Zn sites. For propylene, the allyl anion adsorbed on Zn sites reacts with PBN, but the resulting hydroxylamine must be oxidized before a nitroxide radical can be observed. Less than 1% of the adsorbed species are detected by the spin trapping technique.