Ultra-high Vacuum - Typical Uses For Ultra-high Vacuum

Typical Uses For Ultra-high Vacuum

Ultra-high vacuum is necessary for many surface analytic techniques such as:

• X-ray photoelectron spectroscopy (XPS)
• Auger electron spectroscopy (AES)
• Secondary ion mass spectrometry (SIMS)
• Thermal desorption spectroscopy (TPD)
• Thin film growth and preparation techniques with stringent requirements for purity, such as molecular beam epitaxy (MBE), UHV chemical vapor deposition (CVD) and UHV pulsed laser deposition (PLD)
• Angle resolved photoemission spectroscopy (ARPES)

UHV is necessary for these applications to reduce surface contamination, by reducing the number of molecules reaching the sample over a given time period. At 0.1 mPa (10−6 Torr), it only takes 1 second to cover a surface with a contaminant, so much lower pressures are needed for long experiments.

UHV is also required for:

• Particle accelerators
• Gravitational wave detectors such as LIGO, VIRGO, GEO 600, and TAMA 300.
• Atomic physics experiments which use cold atoms, such as ion trapping or making Bose-Einstein condensates

and, while not compulsory, can prove beneficial in applications such as:

• Atomic force microscopy. High vacuum enables high Q factors on the cantilever oscillation.
• Scanning tunneling microscopy. High vacuum reduces oxidation and contamination, hence enables imaging and the achievement of atomic resolution on clean metal and semiconductor surfaces, e.g. imaging the surface reconstruction of the unoxidized silicon surface.