原子探针工作原理及其在地球科学中的应用

An Introduction to Principle of Atom Probe and its Applications in Earth Sciences

原子探针层析技术可提供亚纳米分辨本领下元素的三维成分和空间图像信息。与其他微束分析技术不同的是,原子探针分析是将样品做成曲率半径小于100 nm的针状,在样品尖端接入高压使其处于待电离状态,通过脉冲电压或脉冲激光来逐层蒸发原子,以飞行时间质谱仪测定蒸发离子的质荷比,从而确定元素种类,以位置敏感探头回溯离子在样品尖端的二维坐标,通过离子在纵向的逐层累积,确定离子的纵向坐标,进而通过计算机软件重构整个样品的三维结构信息,其横向分辨率为0.2 nm、深度分辨率为0.1 nm。本文通过回顾原子探针技术发展历史,简述其工作原理和地质应用,以期引起国内地质学界的关注和兴趣,在基础地球科学问题研究上取得新认识。

Atom probe tomography(APT)can be used to provide quantitative information of three-dimensional components and spatial distribution of elements under the sub-nanometer resolution.It is different from other kinds of micro-analysis techniques,as its sample must be prepared in needle shape with the radius of curvature less than 100 nm in order to let the tip of the sample needle be in an standing ionization state after it was connected to the high voltage electric power.The atoms are vaporized layer by layer by pulsed voltage electric power or laser.The mass spectra peak and mass/charge ratio of vaporized ions are measured by using the time-of-flight mass spectrometer in order to identity types of elements.The 2 D coordinates of the tip of sample needle are recorded by the position sensitive detector.Meanwhile,the longitudinal coordinates of ions are determined by the accumulation of ions layer by layer in the longitudinal direction.Then the 3 D structural information of the whole sample is reconstructed by using the computer software,with the lateral resolution of 0.2 nm and the vertical resolution of 0.1 nm.In this paper,we have reviewed the development history of APT,briefly introduced the working principle of APT and its applications in geosciences,in order to attract domestic geologists’attention and interest.It can be predicted that the application of APT will be helpful to get new understandings in the research of Earth sciences.