CdO and ZnO Clusters as Potential Building Blocks for Cluster-Assembled Materials: A Combined Experimental and Theoretical Study

Small semiconductor nanoclusters exhibit unique properties often very different from those of their atomic and bulk counterparts. Their better understanding and characterization is expected to be useful in the development of highly functional cluster-assembled materials (CAMs) with tunable properties. In this work, the structural and electronic properties of size-selected (CdO)_n^– clusters were examined by conventional and time-resolved spectroscopy (TR-PES) combined with density functional theory (DFT) calculations. The observed highly symmetric alternant-cage structures and large band gaps confirm the validity of those species as CAM building blocks. Moreover, our results demonstrate a striking similarity between (CdO)_n^– and (ZnO)_n^– clusters of the same size that is not restricted to the ground state but also comprises properties of excited states. We suggest that in general valence isoelectronic small binary (XY)_n clusters might exhibit similar structures and comparable properties. The long lifetimes of excited states observed in our experiment are proposed as a general probe helpful in identifying suitable structures for CAMs and hence simplifying their design.