赤外多光子解離分光による気相金属クラスター表面に吸着したNOの吸着構造の解明

抄録

Precious metals, including Rh, are used practically in three-way catalytic converters of automobiles. An important role of Rh is the reduction of NO_x to N₂. Gas-phase clusters are used to study reactions relevant to heterogeneous catalysts because it is possible to define and detect the number of atoms included in the cluster and to obtain atomic-level insights into the reactions. We have studied the adsorption forms of NO molecules on metal clusters by using infrared multiple photon dissociation (IRMPD) spectroscopy. We found that NO molecules adsorb on metal clusters molecularly or dissociatively depending on the element and the size of the clusters. For instance, NO adsorbs on Rh_n^＋ clusters mainly in the molecular form (＞95% on Rh₆^＋), while more NO adsorbs dissociatively on Ir_n^＋ clusters (～50% on Ir₆^＋). In this review, the methodology and results of the identification of NO adsorption forms on Rh and related clusters are presented.