In collaboration with CLS staff, the beamline team (BT) will design, construct, and operate a soft X-ray undulator based beamline dedicated to spectromicroscopy studies of materials and biological systems. Two types of microscopes are proposed - a zone plate based scanning transmission X-ray microscope (STXM) and an X-ray photoelectron emission microscope (X-PEEM). The proposed science includes: soft material studies, mainly polymers (Hitchcock, Urquhart, Dutcher, Stover) and biomaterials (Hitchcock, Gardella); environmental and natural resources issues (Brown, Martin); tribology (Bancroft, Kasrai, Norton); technologically oriented surface science (Norton, Roy, Guay), and magnetic thin film structures (Robertson et al.). Innovations in the instrumentation include: an elliptically polarised undulator with full polarisation control; an advanced STXM design (interferometric tracking, high level of automation; planned extension to cryogenic sample temperatures); and a mobile PEEM to provide surface analytical microscopy over a wider photon energy range than will be available at the STXM spectromicroscopy beam line. Development of novel aspects of microscope instrumentation and acquisition/analysis, including advanced detector developments, will be an important aspect of BT activities (Hitchcock, Tyliszczak). The research of the BT is estimated to be ~70% academic and ~30% fee-for-service or proprietary.
The research challenges which our beamline team deal with are ones which can best be addressed using light in the soft X-ray region (wavelengths from 6 nm to 120 nm).
|In one technique, called scanning
transmission X-ray microscopy (STXM), the light is focussed to 50 nm
and images are made by scanning the sample under the fixed small spot.
The focussing element, called a zone plate, works with only the coherent
(laser-like) part of the synchrotron light beam. For this reason, a third
generation light source like CLS is optimal. With STXM we will explore
many materials - polymers, cells, plants, soil, minerals, wood, etc - with
the goal of understanding the chemical basis for fine scale structure which
often controls the properties or determines the function. Improved understanding
of the chemical basis of nano- and microstructure is a critical part of
developing better materials, medical procedures, environmental problem
In a second technique, called X-ray photoelectron emission microscopy (X-PEEM), the electrons produced by X-ray ionisation are used to form an image by expanding the spatial distribution with an electrostatic or magnetic lens like those used in electron microscopes. Here the requirements for the synchrotron light are less demanding so the X-PEEM will be capable of being moved to any of the CLS beam lines. X-PEEM detects photo-ejected electrons which can only escape from a very thin surface layer. X-PEEM will be used to study surface and thin film phenomena such as: protective films formed by oil additives in car engines, magnetic structures such as those used in the computer recording industry, polymers in contact with blood, such as those used in artificial hearts. X-PEEM and STXM are related and complementary techniques.
The mission of the spectromicroscopy group is to build high performance soft X-ray spectromicroscopy instrumentation and to develop a strong national and international user community, with participation by academic, industry and government researchers. last changed: 13-sep-01 (aph)