Principle and structure of Scanning probe microscopy
The basic working principle of Scanning probe microscopy is to use the interaction between the probe and the atoms and molecules on the sample surface, that is, when the probe and the sample surface are close to the nanometer scale, the physical fields of various interactions are formed, and the surface morphology of the sample is obtained by measuring the corresponding physical quantities. The Scanning probe microscopy consists of probe, scanner, displacement sensor, controller, detection system and image system.
The controller moves the sample in a vertical direction through a scanner to stabilize the distance (or physical quantity of interaction) between the probe and the sample at a fixed value; Simultaneously move the sample in the x-y horizontal plane, so that the probe scans the surface of the sample along the scanning path. The Scanning probe microscopy detects the relevant physical quantity signals of the interaction between the probe and the sample when the distance between the probe and the sample is stable; Under the condition of stable interaction physical quantities, the distance between the probe and the sample is detected by a vertical displacement sensor. The image system performs image processing on the surface of the sample based on the detection signal (or the distance between the probe and the sample).
According to the different physical fields of the interaction between the probe and the sample, the Scanning probe microscopy is divided into different series of microscopes. Among them, Scanning tunneling microscope (STM) and Atomic force microscopy (AFM) are two commonly used Scanning probe microscopy. The Scanning tunneling microscope detects the surface structure of the sample by detecting the tunnel current between the probe and the measured sample. The Atomic force microscopy detects the surface of the sample by detecting the micro cantilever deformation caused by the interaction force between the tip and the sample (which may be attractive or repulsive) through the photoelectric displacement sensor.
