 |
The Extreme Ultra-Violet Spectroscopy Group |
 |
| Introduction
People News |
The XUV research areas extend from ozone layer chemistry to microelectronics. Scroll down to read about the XUV group. |
|
|
| Our research is focused on probing into the fundamental properties of
matter using synchrotron radiation in the photon energy range 10 to 350
eV. To achieve this we employ a variety of techniques, principally
photoelectron spectroscopy, ion spectrometry and fluorescence
spectroscopy, with which we can determine the electronic structure of
atoms and molecules both in the gas phase and when bonded to solid
surfaces. Angular resolution allows us to investigate the symmetry of
atomic and molecular orbitals, to detect subtle electron correlation
effects and to examine the geometry of surface structures. Photoelectron
spectroscopy is refined even further with the use of polarimeters to
measure the spin of ejected electrons, useful in studying surface
magnetism and the properties of chiral molecules. The group is currently responsible for five operational stations on the SRS, the most recent of these is a station on Multi-pole Wiggler 6, MPW6.1, whose construction was funded by an EPSRC grant. Station 3.2: beamline equipped with a 5 metre McPherson normal incidence monochromator to give high resolution in the range 5 to 35 eV; mainly used for gas phase studies. Station 3.3: a toroidal grating monochromator produces light from 10 to 120 eV; mainly used for gas phase studies and surface science experiments involving circularly polarized light. Station 5D (5.3): new advanced VUV beamline designed to provide linearly or circularly polarized light from 10 to 180 eV. "Phoenix" Multi-Pole Wiggler 6.1: a 40 to 350 eV soft X-ray beamline for the physical sciences which will break new ground using the very high flux available from a multipole wiggler magnet. In collaboration with the VUV-IR facility group, an upgrade of station 3.1 is being carried out, supported by an EPSRC grant held jointly with Birmingham University. The Seya monochromator is being replaced by a high flux normal incidence instrument of the Wadsworth type, providing an order of magnitude more flux than previously available in the wavelength range 40nm to 250nm. It will be used for molecular photochemistry studies and circular dichroism studies of biological molecules. We can also deploy an array of offline facilities, which are used alongside our synchrotron stations in support of two main scientific areas, Atomic & Molecular Science and Surface Science. A review of the XUV group was carried out in January 2001, and a report is available. |
Atomic & Molecular Science |
| At Daresbury we have facilities for measuring angle resolved
photoelectron spectra and photo-absorption spectra; but the diversity of
gas phase experiments generally means that users bring their own equipment
and attach it to the beamline which covers the required spectral range.
All of the XUV group stations can be used for gas phase work along with
station 3.1 of the VUV-IR
group and undulator beamline 5U1 of the SXR group. Experiments undertaken
include threshold electron spectroscopy, photo-fragmentation studies and
photo-electron-photo-ion coincidence measurements, some of which are
featured in our research highlights
page.
Support for this program is provided by the Atomic & Molecular Science Laboratory. A Network on Molecular Studies with Synchrotron Radiation has been funded by the EPSRC Physics Programme. |
Surface Science |
| Surface science experiments require ultra-high vacuum, which means
that equipment is bulky, complex and expensive; so the experimental
chambers are fixed and serve many different users. Support for this
program at all photon energies is provided by the Surface Science Laboratory, who can
offer a selection of end-stations, detectors and analysers for use in a
wide variety of experiments.
Surface science experiments can be carried out on XUV group stations 5D, 3.3 and MPW 6.1 "Phoenix"; and stations 1.1, 4.1 and 5U1 of the Soft X-Ray group. There is also a surface science user group. |
Spin Polarized Spectroscopy |
| The study of surface magnetism is undertaken using the technique of spin polarized electron spectroscopy, in which the spin of photoemitted electrons is determined using Mott polarimeters. The main user facility in this area is SPS-1, which houses a retarding potential Mott detector and can be used on all the surface science beamlines. For more information see the SPS lab homepage |
Solid State Luminescence and Optically-Detected EXAFS |
| Synchrotron radiation can be used to stimulate a wide variety of luminescence phenomena in solid state semiconductors and insulators. The energy transfer mechanisms between excitation and emission often mean that the local structure of the host atoms can be probed, if the the luminescence excitation energy is scanned across the K, L and M edges: this gives rise to Optically Detected EXAFS (OD-EXAFS). OD-EXAFS is sometimes much more sensitive than traditional detection methods, and provides a wealth of additional information regarding the energy transfer processes occuring in the samples. For more information see the homepage for MoLES (mobile luminescence end-station) |
  |
Station 3.2 | Station 3.3 | Station 5D | MPW 6.1 |
Page Creator Richard Wain Updated February 2002 |