INFLUENCE OF THE CHEMICAL STATE ON THE LIFETIME OF A NUCLEAR ISOMER, Tc$sup 99$m
INFLUENCE OF THE CHEMICAL STATE ON THE LIFETIME OF A NUCLEAR ISOMER, Tc$sup 99$m
复制标题
化学状态对核异构体寿命的影响，Tc$sup 99$m
DOI：
10.1103/physrev.90.430
复制
发表时间：
1953
期刊：
影响因子：
--
通讯作者：
E. Wilson
中科院分区：
文献类型：
--
作者：
K. T. Bainbridge;M. Goldhaber;E. Wilson
由于核同质异能跃迁可能通过发射γ射线或内部转换电子而发生，因此总衰变率可能会随着电子环境的任何变化而变化，例如化学状态的差异。用双电离室平衡法测量了异构体Tc 9 - 9 m（6小时）在不同化学结合状态下的衰变常数的差异。这种异构体的λ主要由2 keV跃迁的内部转换概率决定，该跃迁之后立即是方便测量的140 keV伽马射线。比较了两个+7价态的化合物：λ（KTc O 4）− λ（Tc 2 S 7）= 27.0±1.0× 10− 4 λ（Tc 2 S 7）。在镍上电镀并在1000 ℃氢气中还原1小时的金属的λ − λ（Tc 2 S 7）= 3.1±1.2× 10− 4 λ（Tc 2 S 7）。误差是标准差。有证据表明，Tc扩散到镍基中，并且与纯晶体金属相比，λ（Tc）在10 4中降低了102份。金属的λ直接测量为0.1148±0.0005 hr− 1，对应于6.04±0.03小时的半衰期（误差限）。说明了用于内部检查数据的方法和装置的操作，并讨论了测量的统计。
Since a nuclear isomeric transition may take place by emission of either a gamma-ray or an internal conversion electron, the total rate of decay may be expected to vary with any change in electronic environment, such as a difference in chemical state. Differences in the decay constant of the isomer Tc 9 9 m (6 hours) in different states of chemical combination were measured by the double ionization chamber balance method. λ for this isomer is determined mainly by the internal conversion probability of a 2-kev transition which is followed promptly by a conveniently measurable 140-kev gamma-ray. Two compounds in the+ 7 valence state were compared: λ (KTc O 4)− λ (Tc 2 S 7)= 27.0±1.0× 10− 4 λ (Tc 2 S 7). λ for the metal electroplated on nickel and reduced in H 2 at 1000 C for 1 hour− λ (Tc 2 S 7)= 3.1±1.2× 10− 4 λ (Tc 2 S 7). Errors are standard deviations. There is evidence for diffusion of the Tc into the nickel base and an accompanying decrease in λ (Tc) of∼ 2 parts in 10 4 compared to pure crystalline metal. λ of the metal was measured directly as 0.1148±0.0005 hr− 1, corresponding to a half-life of 6.04±0.03 hours (limit of error). The methods used for internally checking the data and the operation of the apparatus are illustrated, and the statistics of the measurements are discussed.