Study of the Chemical Effect Accompanyling Nuclear Transformation by Coincidence M ssbauer Spectroscopy

Research Project

Project/Area Number	59840016
Research Category	Grant-in-Aid for Developmental Scientific Research
Allocation Type	Single-year Grants
Research Field	無機・錯塩・放射化学
Research Institution	University of Tsukuba
Principal Investigator	SHOJI Hitoshi Department of Chemistry, University of Tsukuba, 化学系, 講師 (90015553)
Co-Investigator(Kenkyū-buntansha)	SEKI Riki Department of Chemistry, University of tsukuba, 化学系, 講師 (70015775)
Project Period (FY)	1984 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥9,600,000 (Direct Cost: ¥9,600,000) Fiscal Year 1986: ¥300,000 (Direct Cost: ¥300,000) Fiscal Year 1985: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1984: ¥8,800,000 (Direct Cost: ¥8,800,000)
Keywords	coincidence-M ssbauer / Chemical Effect Accompanying Nuclear Transformation / Delayed / coincidence / Substance with Super-conductivity / Cobalt-57 / Ec-decay / 発光メスバウアー分光法 / 同時計数 / 大環状コバルト有機錯体 / 非平衡 / 動的状態 / アンテモン化合物 / テルルの化学状態 / ランダムコインシデンス / メスバウアー分光 / 【^(57)Co】 / ポルフィリン / 【^(125)Sb】 / 【^(125)Te】 / 硫化物 / 不確定性原理
Research Abstract	As the first part of this study, we constructed a Mossbauer-spectroscopic assembly with the coincidence circuit system. This assembly was tested with a ^<57>Co source. It was found that the distinction of a real coincidence from random coincidences was very difficult and that high technique was essential both for electronics and radiochemistry. Although coincidence-spectra from a TAC clearly showed a real coincidence peak on the plateau of random coincidences, the background of the random coincidece is still very high even under the best present conditions. From the several preliminarily tested substances, we chose YBa_2Cu_3O_<7-x> (<equal or less than>x <equal or less than>0.5) with super conductivity below 80゜K for the investigation. This substance has the anomality that its one Cu has (2+x) valence. Special YBa_2Cu_3O_<7-x> cotaining 1 % of ^<57>Fe-enriched Fe was prepared and its spectrum was measured by a usual absorption method at room temperature. Another doped sample was also made in the following way that a slightly acidic solution of carrier-free ^<57>Co^<2+> was doped and that it was heated at 850゜C in air for 3 hours. After removing the surface layer, this sample was subjected to emission M ssbauer spectroscopy at room temp. both in a usual way and time-differential ways under the time conditions of 0[20 and 0[40 ns after the deexcite to the M ssbauer level. In all the cases, the main component of the peak was symmetrical doublet doublet which has very large QS(1[2mm/sec) corresponding to Fe(III). In the emission case, FWHM of the component peaks was much larger than that in the absorption case. It suggests that ^<57>Co introduced might be located at the unstable site with low symmetric oxygen coordination and that tha disturbance due to EC-decay might be added to that in the emission case. The more enlargement of the width in time-differential cases was interpreated to be due to the uncertainity from counting period.