Matsuishi Satoru, Hayashi Katsuro, Hirano Masahiro, Hosono Hideo
Frontier Collaborative Research Center, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
J Am Chem Soc. 2005 Sep 14;127(36):12454-5. doi: 10.1021/ja053568m.
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.
在氢气气氛中加热的12CaO·7Al2O3（C12A7）晶体中，利用电子顺磁共振（EPR）观察到了4K温度下由紫外光照射（波长约330nm）产生的原子氢（H0）和俘获电子。在C12A7亚纳米尺寸笼（F + 中心）中产生的H0与俘获电子的浓度比几乎为1:1，这直接证明了通过热处理容纳在笼中的氢负离子H - 被紫外光子解离为一对H0和一个电子：H - →H0 + e - （F + ）。在300K退火后，H0完全湮灭，而约6%的俘获电子存活下来。剩余的电子可以在相邻的笼之间跳跃，使C12A7具有导电性。C12A7中H0的EPR谱的超精细分裂（48.6mT）比中性氢原子的超精细分裂（50.6mT）小4%，这意味着H0被困在笼间的间隙位置。
