Authors:W. Sato, H. Ueno, A. Taniguchi, Y. Itsuki, Y. Kasamatsu, A. Shinohara, K. Asahi, and Y. Ohkubo
The time-differential perturbed angular correlation (TDPAC) method was applied to a study on the behavior of 140Ce atoms implanted in highly oriented pyrolytic graphite (HOPG). Exponential-type gradual attenuation of the directional anisotropy
of the relevant γ-ray cascade was observed in the perturbation patterns. From temperature dependence of the relaxation rate,
a thermally activated dynamic motion of the probe atoms was suggested.
Authors:Y Kobayashi, M. Kubo, Y. Yamada, T. Saito, H. Ueno, H. Ogawa, W. Sato, K. Yoneda, H. Watanabe, N. Imai, H. Miyoshi, and K. Asahi
In-beam Mössbauer spectra of 57Fe, decayed from short-lived 57Mn (T1/2 = 1.45 min) implanted into potassium permanganate, KMnO4, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional 57Fe atoms for Mn-sites in tetrahedral [MnO4]– with an unusually high valence state of Fe8+.
Authors:W. Sato, H. Ueno, H. Watanabe, H. Ogawa, H. Miyoshi, N. Imai, A. Yoshimi, K. Yoneda, D. Kameda, Y. Kobayashi, and K. Asahi
A new 19F probe disintegrated from short-lived 19O has been developed for the first time for time-differential perturbed angular correlation method. The angular correlation coefficient for the relevant cascade has been experimentally estimated to be A22 = -0.17±0.01. As the first application of this technique to condensed matter physics, the probe was implanted in polycrystalline fullerene C60. We have observed two contrastive perturbations acting on the probe nuclei, which reflect electrostatic and dynamic interactions with the extranuclear field.