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

巧合穆斯堡尔谱研究伴随核转变的化学效应

基本信息

批准号：
59840016
负责人：
SHOJI Hitoshi
金额：
$ 6.14万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1986
项目状态：
已结题

项目摘要

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.

作为本研究的第一部分，我们利用符合电路系统建立了一个穆斯堡尔谱学装置。该组装件用^<57>Co源测试。人们发现，区分真实的符合与随机符合是非常困难的，高技术对电子学和放射化学都是必不可少的。虽然TAC的符合谱在随机符合的平台上清楚地显示出一个真实的符合峰，但即使在目前最好的条件下，随机符合的本底仍然很高<7-x><equal or less than><equal or less than>。该物质具有一个Cu具有（2+x）价的反常性。制备<7-x><57>了含1%Fe的特殊YBa_2Cu_3O_2，并在室温下用普通吸收法测量了它的光谱。另一个掺杂样品也是以如下方式制备的：将无载体的2Co <57>^<2+>的微酸性溶液掺杂，并将其在空气中在850 ° C下加热3小时。去除表面层后，在室温下对该样品进行发射穆斯堡尔谱。在退激到穆斯堡尔能级后的0[20]和0[40] ns的时间条件下，以通常的方式和时间微分的方式。在所有情况下，峰的主要成分是对称的双重峰，其具有非常大的QS（1[2 mm/sec），对应于Fe（III）。在发射情况下，组分峰的半高宽远大于吸收情况。这表明引入的^<57>Co可能位于对称氧配位较低的不稳定位置，并且在发射情况下可能会增加EC衰变引起的干扰。时间差情况下宽度的进一步扩大被解释为是由于计数周期的不确定性。