According to the kinetic theory, at a pressure of the order of 10⁻⁶ torr, a surface would be bombarded at the rate of 10¹⁴–10¹⁵ times/cm²/s. If we assume that the sticking coefficient equals to 1, the surface will be covered by a monolayer of gas molecules in few seconds.

In order to carry out meaningful surface science experiments, it is necessary to maintain the pressure at the order of 10⁻¹⁰ torr so that we could keep a clean surface for a few hours [1]. Our experiments are all performed in UHV chambers equipped with a turbomolecular pump and an ion-pump; the base pressure of these chambers is around 5×10⁻¹⁰ torr.

Scanning Tunneling Microscopy

The Scanning Tunneling Microscopy (STM) was invented by Binning and Rohrer first in 1981 and they were rewarded a Nobel Prize in Physics in 1986 for this invention. According to the electron tunnel current between tip and sample and vertical displacements of the tip, STM gives direct real-space images of sample's surface.

X-ray Photoemisson Spectroscopy

This is the XPS analysis chamber which can be mounted to the BL09A U5 spherical grating monochromator undulator beamline (U5-SGM) at the National Synchrotron Radiation Research Center (NSRRC).

Low Energy Electron Diffraction

Low energy electron diffraction (LEED) is a technique for inspection and survey of the surface by bombardment of low energy electrons (20-200eV).

Reflection High Energy Electron Diffraction

The RHEED system in Nano-scale Physics lab (S4-409) contains RHEED, LEED (Low energy electron diffraction)、 AES (Auger electron spectroscopy), and electrochemical cell for CV (cyclic voltammetry) experiment.

Infrared Reflection Adsorption Spectroscopy

Infrared reflection adsorption spectroscopy is a vibrational spectroscopic method often used in surface science. It involves a single external reflection of an infrared beam at a grazing angle of incidence on the molecules-covered substrate, the molecules absorb radiation according to their vibrational frequencies and corresponding absorption bands appear in the spectrum of the reflected radiation.