Surface Physics Apparatus

We have a wide range of experimental equipment, from novel world-leading apparatus to more standard surface science systems. Our emphasis is on helium atom scattering, for which we are the only UK specialist group.

The Helium-3 Spin-Echo Spectrometer

The Spin Echo Machine is our newest, fully operational system. It provides a truly world class facility, uniquely able to measure surface dynamics (diffusion, vibrations etc.) on picosecond to nanosecond timescales.

Visit the Spin Echo section to find out more.

The Atom Scatterer

The Helium Atom Diffractometer remains one of the best of its type in the world and is capable of a wide variety of experiments, ranging from diffraction studies to analyse surface structure to time of flight measurements to examine surface dynamics.

The machine essentially consists of a very large ultra high vacuum chamber, containing a sample manipulator and detector. The helium beam is produced by the supersonic helium expansion formed when high pressure helium (200 bar) is pumped through a small aperture. A skimmer and series of differential pumping stages are used to separate out a fine beam and keep the main chamber pressure low.

The helium atom beam is directed at a sample crystal. The periodic potential of a crystal surface leads to characteristic diffraction peaks that can be measured and used to examine the surface structure. Time of flight experiments can also be carried out by using a pulsed helium beam created using a beam chopper.

There are a trail of keen atom scatterers leading away from the group, including Ian Shuttleworth, Bodil Holst, Martin Nohlen, Hobson Bullman, Justin Buckland and Donald MacLaren, to name just a few. Further details of the apparatus can be found here.

The MiniScat

The Mini Atom Scatterer is currently being redeveloped as a part of the spin-echo project to provide a separate surface characterisation system, equipped with a rnage of standard surface science apparatus such as TDS (Thermal Desorption Spectroscopy), Auger and LEED.

TDS Rig

In addition to the MiniScat, the group has a separate TDS rig which is available as a surface preparation and characterisation chamber, suitable for a wide variety of experiments - recently having been used for testing the field-emission properties of carbon-nanotube arrays.

AFM/STM

We have recently acquired a state-of-the-art environmental scanning probe microscope with both scanning tunneling microscopy (STM) and atomic force microscopy (AFM) functionality. The instrument is capable of imaging in vacuum, controlled gas phase and liquid environments. The current use of this apparatus is to study the electrochemical reactions used in microelectronic device fabrication. Its goal is to optimise the chemical etching mechanisms to produce ultra-smooth silicon surfaces.