Promotion in solid phase reaction of Pt/SiO_x bilayer film by electron-orbital-selective-excitation

A thermally impossible positive free energy reaction can proceed by electron-orbital-selective excitation. When the Si 2p core level is photo-excited in Pt/SiO _<i>x</i> bilayer films, Coulomb repulsion at the final two-hole state localized in the valence band by an interatomic Auger transition induces dissociation of the O atom and formation of a Si-Pt bond. Consequently, Pt₂Si silicide is formed by a positive free energy reaction. Under a single particle excitation of the valence band, low probability of the coexistence of the two-hole state for picosecond order suppresses to allow the reaction to proceed.