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Updated: Jul 25, 2026

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids
Published on: August 23, 2012
Hydride ion as photoelectron donor in microporous crystal
Satoru Matsuishi1, Katsuro Hayashi, Masahiro Hirano
1Frontier Collaborative Research Center, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8503, Japan. satoru@lucid.msl.titech.ac.jp
Abstract:
Atomic hydrogen (H0) and trapped electrons generated by UV illumination (lambda approximately 330 nm) at 4 K were observed using electron paramagnetic resonance (EPR) in a 12CaO.7Al2O3 (C12A7) crystal heated in a hydrogen atmosphere. The concentration ratio of generated H0 to the electrons encaged in the subnanometer-sized cages of C12A7 (F+ centers) is almost 1:1, providing direct evidence that a hydride ion, H-, accommodated in the cage by the heat treatment was dissociated to a pair of an H0 and an electron by a UV photon: H- --> H0 + e- (F+). After annealing at 300 K, H0 was completely annihilated, while approximately 60% of the trapped electrons survived. The remaining electrons can hop between neighboring cages and give electrical conductivity to C12A7. The hyperfine splitting of the EPR spectrum of H0 in C12A7 (48.6 mT) is 4% smaller than that of the neutral hydrogen atom (50.6 mT), implying that H0 is trapped at the interstitial sites among the cages.
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