文档介绍：Introduction to Atomic Force Microscopy
Yanchun Han
显微镜技术的发展
17 世纪:光学显微镜:微米级, x, y二维
20世纪40年代:电子显微镜:SEM, TEM
5 nm, x, y二维
90年代: AFM: 三维,x,y: 2 nm
Z< nm
优点: 操作容易
样品准备简单
操作环境不受限制
分辨率高
History of Scanning Probe Microscope
Atomic image of Si(7x7)
1981 Heinrich Rohrer and Gerd Binnig develop the first scanning tunneling microscope (STM) at IBM Zurich (Nobel Prize 1986)
In this technique a sharp metal Tip is positioned over the conducting sample. A small potential difference is then applied between the tip and the sample. Electrons "tunnel"through the Gap between the tip and the sample into the tip and vice versa.
The tip is then scanned across the surface of the sample. The signal that gets detected is the Tunnel Current
The result is a Topographical image of atoms on a surface, achieved by recording the tip height at each location.
The Atomic Force Microscope (AFM) was developed from the Scanning Tunneling Microscope (STM) in 1986 by Binning, Quate and Gerber. The limitation of the STM in only being able to image conducting materials was e by the Force Microscope.
This microscope neither needs the sample or the tip to be conductive,a huge development in the imaging of biological surfaces.
The two main Applications of AFM are Imaging and Force Distance Curves.
With regards to imaging, the advances since 1986 have been astonishing. Atomic Force Microscopy Provides quantitative, three-dimensional images and surface measurements with extremely high resolution, which can be of the order of10 to 20 Angstroms.
Many surface structures have been revealed from the first images of lamellar materials in 1987, through to images of DNA, and Proteinsin 1988.
AFM
Scanning Probe Microscopy (SPM)
A family of microscopy forms where a sharp probe is scanned across a surface and some tip/sample interactions are monitored
Scanning tunneling Microscopy (STM)
Atomic Force Microscopy (AFM)
contact mode
non-contact mode
TappingMode (DFM)
LiftMode
Other forms of SPM
Lateral