Chemical properties of size-selected Au clusters treated under ambient conditions

Mass-selected Au clusters consisting of 5–8 atoms deposited on silica were treated with water and aqueous NaOH solution, and the change of their chemical properties upon these treatments was studied. With water, no change was observed, indicating that the clusters survive as individual entities under such realistic conditions. After immersing the samples into the NaOH solution, a change of the oxidation behaviors of the Au clusters was found to occur; the originally oxidation resistant Au5 and Au7 become more reactive than the other clusters towards oxidation. Non-scalable chemical behaviors can be obtained from the small clusters even under realistic conditions.