【求助】二次电子像，背反射电子像的概念

首先做個更正是背散電子﹐不是背反電子﹗
二次電子主要是看結構成像.
背散電子主要是看組成成像.

sorry,我寫錯了！能否說詳細點呢?TKS

Many signals exit the sample as a result of the incident electron beam interacting with the material. These include backscattered electrons, econdary electrons, Xrays, uger electrons, athodoluminescence, ect transmitted lectrons if thin enough.

Electrons that form secondary electron images are of very low energy, typically 50eV, and therefore have only sufficient energy to escape from only a very thin surface layer of less than 10nm depth where the beam has not yet spread significantly in the lateral direction. As a result, the spatial resolution of secondary electron images is greater than Xray analysis.

Higher energy backscattered electrons escape from greater depths and hence these images are poorer in spatial resolution than secondary electron images. In addition, X-rays can continue to be generated by the primary beam and, being able to travel farther in matter than electrons, escape from still deeper from within the sample.

入射电子与样品核外电子碰撞使后者脱离原子变成二次电子，二次电子能量很低（小于50ev),二次电子所成的像反映了样品表面的形貌，是扫描电镜的主要用途。
背散射电子是入射电子被样品反射回来的一次电子。用背散射电子获得的图像有两种情况：一种可以反映样品表面的形貌与二次电子相似，它的优点是较稳定，不受充电效应和污染的影响，缺点是分辨率较低：另一种情况是反映样品的密度和原子序数。你用这种特性，可以将生物组织中各种细胞用重金属染色，再把它检测出来。这种组织化学和扫描电镜结合的方法已受到广泛重视。

這個講的不錯.挺請楚的

這個講的不錯.挺請楚的

学习了，谢谢！