电喷雾串联质谱模拟天然单质铀的形成

Simulating Formation of Natural Native Uranium by Electrospray Ionization Tandem Mass Spectrometry

采用三重四级杆质谱模拟并分析微观含铀分子化学键断裂形成新的物质的过程以探讨单质铀的产生机理。结果表明,含铀分子在质谱中离子化后经碰撞诱导解离可生成U^+。研究还发现,硝酸铀酰溶液通过电喷雾可形成UO^+_2(m/z 270)、UO_2OH^+(m/z 287)、UO_2H_2OOH^+(m/z 305)、UO_2NO^+_3(m/z 332)、UO_2(H_2O)_3NO^+_3(m/z 386)及双聚铀酰离子[(UO_2NO_3H_2O)_2NO_3]^+(m/z 762),在具有一定动能N_2的碰撞下它们均可产生游离的U^+。通过模拟实验推测,天然单质铀形成的微观机理为:在漫长地质年代中放射性核素持续衰变产生的能量粒子撞击含铀分子使其化学键断裂生成游离铀离子,在封闭或强还原性等特殊地质条件下形成单质铀并被保存下来。

To explore the formation mechanism of uranium, electrospray ionization tandem mass spectrometry was used to simulate and analyze the chemical bond breaking of uranium-containing molecules. The results show that U^+ is generated in collision induced dissociation mode after uranium-containing molecules were ionized in mass spectrometry. By further study it is found that there are UO^+2 (m/z 270), UO2OH^+(m/z 287), UO2H2OOH^+(m/z 305), UO2NO^+3(m/z 332), UO2(H2O)3NO^+3(m/z 386) and bis-uranyl ion [(UO2NO3H2O)2NO3]^+(m/z 762) in the solution, all of which could form U^+ under the collision of N2 with kinetic energy. The formation mechanism of natural native uranium deducted from simulation experiment is the following: Free uranium cations are generated from the breaking of uranium-containing molecules by collision of neutral particles which are the decay products of radioactive substance, and further, uranium cations form natural native uranium and is preserved in closed or strong reduction geological conditions in a long geological period.