Surface science - the experimental challenge
Determining the atomic structure, chemical behaviour and electronic properties of a surface or interface is challenging. Typically we need to produce well characterised surfaces and keep them atomically clean for the duration of the experiment. This requires ultra-high vacuum (UHV) and the routine application of techniques such as low energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The Warwick laboratories are well equipped, with seven separate UHV systems incorporating one or more of these techniques as well as more specialised equipment.
Compared to the bulk of a typical crystalline material, the number of atoms to be probed by any technique is tiny, leading to potential problems with surface specificity (are we measuring the surface or the bulk?) and surface sensitivity (can we obtain a sufficiently large signal from the surface alone?). Because a given surface structure or epitaxial interface can rarely be understood using a single method, our scientific work depends on several sophisticated experimental techniques able to overcome these difficulties. Most of the group's projects involve combining several experimental approaches, along with theoretical methods, to gain a comprehensive picture of a given surface, interface or material.
Here is a nice introductory video on UHV technology.
The Warwick surface & interface experimental programme
The experimental programme is based on a combination of Warwick-based laboratory experiments and the use of central facilities within the UK and overseas. Follow the links below for further details on the specific methods.
Basic characterisation methods - LEED, RHEED, XPS, AES
Surface electronic properties - HREELS, XPS
Ion scattering - CAICISS, MEIS
Epitaxial growth - MBE
Synchrotron radiation techniques - NIXSW, PhD
Atomic scale microscopy - STM
Auger electron spectroscopy
X-ray photoelectron spectroscopy
Angle-resolved photoemission spectroscopy
Low energy electron diffraction
Reflection high energy electron diffraction
Molecular beam epitaxy
Coaxial impact collision ion scattering spectroscopy
Medium energy ion scattering
Normal incidence X-ray standing waves
Scanning tunnelling microscopy