Study on catalytic properties by soft-landing of gas-phase clusters of metal-oxide and -sulfide

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Gas-phase clusters consisting of 3-1000 atoms have attracted much attention, because they can be regarded as a minimum unit for optoelectronics and magnetism to develop new catalysis and new functional materials. Especially, metal oxide have been utilized widely in catalytic chemistry for so long time that the properties of metal oxide clusters would be of improtance to generate selective and active catalyst. Based upon this viewpoint, the following three results can be obtained.(1) Organometallic cluster complexes coud be successfully synthesized in the gas phase by isolating metal atoms with organic ligands. One dimensional poly-ferrocene was synthesized for the first time, where a couple of metal atoms were sandwiched by radical organic ligands. This result gives fundamental insight to evaluate the electron spin state of the complexes as well as the functionality.(2) The electronic structure of yttrium oxide clusters was observed by photoelectron spectroscopy of their anions. For transition metal oxide clusters, furthermore, electronic structure and adsorption reactivity of NH_3 were measured.(3) The methodology of soft-landing of size-selected cluster was successfully established for organometallic clusters. The organometallic cluster ions, produced by laser ablation with reaction toward benzene vapor, were size-selected and deposited into a low-temperature Ar matrix. Infrared spectrum of V_1 (benzene)_2 in the Ar matrix was measured after 1-hour deposition with the deposition energy of 20 eV.The spectrum was in agreement with both the reported spectrum, showing that V_1 (benzene)_2, prepared in the gas phase reaction, takes a sandwich structure and that the ions were soft-landed onto the Ar matrix and were neutralized by charge transfer from a metal substrate without fragmentation.These results indicate that the soft-landing method can open up a new approach for fabricating new materials with the deposition of the gas-phase clusters.