The Hydroxyl Migration Mechanism through Vibrational Rocking Unveiled from Magic-Numbered Hydrated Lanthanum Oxide...

A deep understanding of the structural evolution of metal oxide clusters and the migration of surface functional groups is of fundamental importance for understanding their catalytic mechanisms. However, due to the structural complexity and the difficulty in the generation and characterization of these species, such a study at the molecular level is still challenging. Herein, a series of magic-numbered cluster ions of hydrated lanthanum oxide were studied by combining laser ablation mass spectrometry, infrared photon dissociation spectroscopy, and theoretical calculations. Based on the identified most stable isomers of the clusters, a new mechanism for OH migration has been revealed, in which the vibrational rocking of OH groups results in the migration of OH groups on the surfaces of the clusters with an energy barrier less than 12 kcal/mol. This work reveals the rocking-induced OH migration process and corresponding energy barriers, shedding light on the effects of rocking vibration modes on the mobility of OH groups and possible subsequent impacts on surface catalysis.