Abstract
The infrared (ir) absorption spectrum of Ca containing hydrogen has been measured over the range 590-2000 . A strong, sharp line observed at 640±0.5 has been assigned to the localized mode of vibration associated with the interstitial neutral hydrogen atoms. The concentration of atomic hydrogen in the Ca has been determined using both ir absorption and ESR absorption techniques. The measured concentration of 3×/, together with the observed integrated absorption of the 640- line of 73 , indicates that the hydrogen-atom defect has an "apparent charge," as defined by Leigh and Szigeti, of 0.07 electrons. The observed localized-mode frequency has been compared with the result of an ab initio calculation of the interaction between the hydrogen defect and its eight fluoride neighbors. This calculation began with a Hartree-Fock-Roothaan self-consistent-field molecular-orbital calculation of the energy of an H molecule. A localized-mode frequency of 560 was obtained, in fair agreement with the observed frequency.
- Received 18 January 1968
DOI:https://doi.org/10.1103/PhysRev.170.822
©1968 American Physical Society