Microscopy and Surface Analysis

Probe Scanning Microscopy

Microscopy and Surface Analysis
It consists mainly of Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM).
STM works by scanning a metal tip on the surface. By bringing the metal tip very close to the surface, and applying an electrical voltage to either the tip or the sample, an image of the surface can be obtained on an extremely small scale.

Surface Analysis

Microscopy and Surface Analysis
X-Ray Photoelectron Spectroscopy (XPS), Time of Flight - Secondary Ion Mass Spectrometry (TOF SIMS) and Low Energy Ion Scattering (LEIS).
XPS is when an atom or molecule absorbs an X-ray photon and an electron is ejected. The kinetic energy (KE) of the electron depends on the energy of the photon (hv) and the bond energy (BE) of the electron. By measuring the kinetic energy of the emitted electrons, it is possible to determine which elements are near the surface, their chemical states and the bonding energy of the electron.
In a TOF-SIMS analysis, a solid surface is bombarded by primary ions of some energy keV. The energy of the primary ion is transferred to atoms of interest via atomic collisions and a collision cascade is generated. The interaction of the collision cascade with the surface molecules is smooth enough to allow even large, non-volatile molecules with masses up to 10,000µ to escape with little or no fragmentation.
In a LEIS analysis the sample surface is bombarded with noble gas ions and an energy of some keV. The ions are dispersed by the surface atoms according to the laws of conservation of energy and momentum. By measuring the energy of the backscattered ions, the mass of the scattered surface atoms is determined

Electronic Microscopy

Microscopy and Surface Analysis
This technique is based on the interaction of electrons with matter and how to obtain both structural and defect characterization information.
In Scanning Electron Microscopy (SEM), low energy (less than 50 eV) secondary electrons are emitted from the sample surface and can be used to give a type of image.