摘要: Infrared photodissociation spectroscopy of mass-selected MO(CO_2)_n^+ (M=Sc, Y, La) complexes indicates that the conversion from the solvated structure into carbonate one can be achieved by the ScO^+ cation at n=5 and by the YO^+ cation at n=4, while only the solvated structures are observed for the LaO^+ cation. These findings suggest that both the ScO^+ and YO^+ cations are able to fix CO_2 into carbonate. Quantum chemical calculations are performed on MO(CO_2)_n^+ to identify the structures of the low-lying isomers and to assign the observed spectral features. Theoretical analyses show that the YO(CO_2)_n^+ complex has the smallest barrier for the conversion from the solvated structure into carbonate one, while LaO(CO_2)_n^+ exhibits the largest conversion barrier among the three metal oxide cations. The present system affords a model in clarifying the effect of different metals in catalytic CO_2 transformation at the molecular level.