当电子束照射固体试样时，就像是向微观世界发送探测器，会产生多种信号回馈给我们：
I0是入射电子流，单位是A，就像是我们发送的”探测信号”。描述入射电子的另一物理量是电子束流密度，单位是A/cm²，表示信号的集中程度。
IR为背散射电子流，包括两种：
一种是被样品表面原子反射回来的入射电子（弹性背散射电子），它们几乎没有能量损失，就像是从硬墙壁弹回的球。
另一种是入射电子进入固体后通过散射改变方向，最后又从样品表面发射出去的电子（非弹性背散射电子），它们已经损失了部分能量，就像是穿过迷宫后找到出口的探险者。
IS表示二次电子流，由直接击出的原子核外电子和退激发产生的发射电子（如俄歇电子）构成。前者称为（真）二次电子，能量较低；后者称为特征二次电子，能量取分立值。这些就像是被我们的探测信号”惊动”而逃离的原子居民。
IA为样品吸收电流。入射电子在固体中传播时，能量逐渐减小，最后失去全部动能，被样品”吸收”，就像是迷失在迷宫中的探险者。
IT为透射电子流。当样品足够薄时，部分入射电子能够穿过样品，在背面被接收或检测，就像是穿越隧道的光线。
对导电样品（接地），如果忽略透射方向的二次电子发射和表面元素脱附对样品总电荷量的影响，上述电子信号之间满足能量守恒关系：I0=IR+IS+IA+IT
这些信号就像是微观世界的”密语”，携带着关于固体材料结构、成分、表面状态等性质的丰富信息，通过解读这些信号，我们能够看到肉眼无法直接观察的微观世界。---**Chart/Diagram Description:**
* **Type:** Schematic diagram illustrating the interaction of an electron beam with a solid sample and the resulting signals.
* **Main Elements:**
* An incident electron beam, labeled I₀, is shown as a thick arrow entering the sample from the top.
* A horizontal line represents the surface of the sample.
* Below the surface, a bulbous shape depicts the interaction volume of the electron beam within the sample, divided into different regions (suggesting varying interaction depths or types).
* Several types of signals are shown originating from the interaction volume and exiting the sample:
* **表面元素发射总强度 (Total intensity of surface element emission):** Labeled Iₓ, shown as wavy lines originating from the surface area and spreading outwards.
* **二次电子流 (Secondary electron current):** Labeled I_S, shown as dashed arrows originating from the surface area and pointing upwards.
* **背散射电子流 (Backscattered electron current):** Labeled I_R, shown as dashed arrows originating from slightly below the surface and pointing upwards.
* **透射电子流 (Transmitted electron current):** Labeled I_T, shown as arrows passing through the bottom of the interaction volume, indicating electrons transmitted through the sample.
* An arrow labeled I_K is shown pointing upwards from the surface near the incident beam impact point.
* **样品吸收电流 (Sample absorption current):** Labeled I_A, shown as a connection from the sample volume to ground, indicating a measured current.
* **Relative Position and Direction:** The incident beam (I₀) enters from the top, perpendicular to the horizontal sample surface. Iₓ, I_S, I_R, and I_K are shown exiting the sample upwards or outwards from the surface region. I_T is shown exiting downwards through the sample. I_A is measured from the sample volume to ground.
* **Labels and Annotations:** All labels and current symbols (I₀, Iₓ, I_K, I_R, I_S, I_T, I_A) are explicitly written near their corresponding arrows or connections. Chinese labels describe the physical meaning of the signals: "表面元素发射总强度", "背散射电子流", "二次电子流", "透射电子流", "样品吸收电流".
**Extraction Content:**
The image provides a diagram illustrating the interaction of an electron beam (I₀) with a sample. The diagram shows various signals generated:
- Surface element emission total intensity (Iₓ)
- Backscattered electron current (I_R)
- Secondary electron current (I_S)
- Transmitted electron current (I_T)
- Sample absorption current (I_A)
- Another signal labeled I_K originating from the surface.
No questions, options, or additional explanatory text are present in the image provided.