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地质学家总是依据混杂在土中的有机物的放射性碳来测定沉积地层的年代.但是沉积物中并不总是含C~(14),且当地层的年代大于7万年时便超出了这种技术的测量范围.最近,David Huntey等人用直接测量沉积矿物颗粒的新方法解决了这些问题.这一新技术的基础是天然同位素衰变产生的辐射能量使电子从原子中游离出来,这些电子又落入晶体缺陷之中.如果这些矿物颗粒受到光的照射,便逃离晶体缺陷.一旦沉积物被埋藏,电子不能逃离晶体缺陷而堆积于晶体缺陷之中.因此,根据被捕获的电子数目就可测量从最后一次曝光起所经历的时间,这样便可推算出该沉积物的堆积年代.正如在《自然》(1985年1月10日,)所讨论的.研究者们用氩离子激光器来激发沉积物样品晶体缺陷中的电子.这些电子返回结晶原子中时释放出的光辐射总量,与这段时间矿物颗粒接收的离子化辐射总量是相关的.再结合放射剂量速率,便可确定该矿
Geologists always determine the ages of sedimentary formations based on the radioactive carbon of the organic matter mixed in the soil, but the sediments do not always contain C 14, and when the age of the formation is more than 70,000 years Recently, David Huntey et al. Solved these problems with a new method of directly measuring the deposition of mineral particles, which is based on the radiative energy generated by natural isotope decay liberating electrons from the atoms, which Electrons fall into crystal defects and if these mineral particles are exposed to light, they escape crystal defects, and once the deposit is buried, the electrons can not escape the crystal defects and accumulate in the crystal defects, so that depending on the number of electrons trapped We can measure the time since the last exposure so that we can deduce the age of the sediment accumulation, as discussed in Nature, January 10, 1985. The researchers used an argon ion laser To excite electrons in the crystal defects of the sediment sample.The total amount of light radiation released when these electrons are returned to the crystalline atoms and the total amount of ionizing radiation received by the mineral particles during this time is Related, combined with the radiation dose rate, can determine the mine