Hydride Ion as Photoelectron Donor in Microporous Crystal

摘要

We succeeded in observing the EPR signal for H~0 in C12A7 after UV illumination at 4 K. The concentration of generated H~0 is almost equal to that of F~+. This observation demonstrates that H~- is trapped in the cage of C12A7 in place of O~(2-) and is photodissociated to a pair of H~0 and F~+. According to the quantum-chemical calculation based on an embedded cluster model, the remaining electron is localized in the cage. This calculation also shows that hopping of electrons between cages results in electrical conduction with a relatively small activation energy of ～0.1 eV. Although the resulting electron is localized in the cage, the densely packed structure of empty cages in C12A7 enables hopping conduction of electrons throughout the lattice. This situation originates from the unique network topology that is completely different from that of conventional ionic crystals, such as alkali—halides, which consist of densely packed ions.