1、第七章 放射性同位素地球化学o同位素计时o同位素示踪o能量特征第六章 放射性同位素地球化学 放射性同位素衰变原理 Rb-Sr同位素 Sm-Nd同位素 U-Th-Pb同位素 Rb-Sr-Pb同位素示踪 K-Ar同位素 C同位素I.衰变反应和衰变定律o不稳定的原子会自发地放射粒子和能量而转变成另外一种原子，这就是放射性衰变；I. Development of Atomic Structure In 1898, Marie Curie isolated polonium and radium from uranium ore which emitted rays that could darken
2、photographic plates.B. RadioactivityMarie Curie (1867-1934) Marie Curie postulated that these rays were omitted as the atoms disintegrated. She named the phenomenon radioactivity. Curies discovery of radioactivity contradicted Daltons Atomic Theory that stated that atoms were indivisible.John Dalton
3、 (1766-1844)I. Development of Atomic Structure Curies early experiments identified three kinds of radiation.B. Radioactivity1. (alpha) particles (+2 charge and high mass)2. (beta) particles (-1 charge and low mass)3. g (gamma) particles (no detectable charge or mass)同位素地球化学基础1、自然核衰变的种类o衰变重核通过放出 质点（ He核），通式为：AZM = A-4Z -2M + , 例如：22688Ra = 22286Rn + Alpha DecayAvailable to elements with atomic numbers greater than 58I.衰变反应和衰变定律o衰变原子核中的中子分裂为质子和电子：AZM = AZ+1M+ - ,例如：8737Rb = 8738Sr + -4019K = 4020Ca + -
