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砹的发现 1931年Allison等,利用磁光测量的方法,在海水中、澳化钾试样和萤石、磷灰石、钾盐镁矾等矿物中,发现元素85。当时命名为啦(alabamine),但以它的半衰期很短,对在自然界中能否存在发生怀疑。 1940年Corson,Mackenize和Segre等用60时迴旋加速器产生氦核轰击Bi~(209),引起(α,2n)反应,第一次制得At~(211),半衰期为7.5小时,衰变性质为40％α发射,60％轨道电子俘获。从此元素85的存在才肯定证实,并且命名为砹(astatine),它的含义是希腊文不稳定的意思。
Found in 1931 Allison, etc., the use of magneto-optical measurement method, in seawater, Australia potassium sample and fluorite, apatite, potassium and other minerals found in trace elements magnesium 85. At that time it was named alabamine, but with its short half-life, doubts about its existence in nature. In 1940, Corson, Mackenize and Segre bombarded Bi ~ (209) with a 60-hour cyclotron and caused (α, 2n) reaction. At ~ 211 was obtained for the first time with a half-life of 7.5 hours. 40% alpha emission, 60% orbital electron capture. Since then, the existence of element 85 was affirmed and it was named astatine, which means the meaning of the Greek is not stable.