Photoelectron Spectromicroscopy
Important work in the U.S.A. on molecular
ions had appeared which used the methods of ion cyclotron resonance, featuring
ions trapped in a magnetic field. In attempting to combine ion cyclotron
resonance with photoelectron spectroscopy, Turner's group accidentally stumbled
on a new possibility. The Part II project (which gained a Thesis prize for Graham
Beamson) and his subsequent work for D.Phil. failed in its purpose of
demonstrating TRIPES (Trapped Ion Photoelectron Spectroscopy) but succeeded in
showing the way to a new kind of electron microscope, the Photoelectron
Spectromicroscope (PESM). Hamish Porter played a key role in the analysis of
its possibilities.
After much fruitless touting of the TRIPES
idea round industry, the Paul Fund had stepped in as it had done with the
original PES idea at Imperial College, and provided the crucial high field solenoid.
When a microscope seemed possible, however, suppport from Thor Cryogenics and
more recently Kratos Analytical was secured, and with Ian Plummer a working
prototype was constructed and demonstrated. Critical lack of funding in the
mid-80's again made further work slow and almost lost the whole project to the
U.S.A., but the laboratory now has a unique facility, the only energy-analysing
photoelectron microscope with demonstrated performance from thermal to X-ray
energies. The great sensitivity which this magnetically collimated class of
instrument gives has already led to new observations of exo-electron emission
images from certain solids. These are extremely low energy electrons. At the
other extreme are X-ray photoelectron images which show a chemically controlled
contrast.
A new commercially viable prototype is
expected to be delivered to the PCL for further work by September, 1991. This
will be the first such machine to have full UHV capacity for clean surface
studies at a spatial resolution to less than 1 micron. The energy resolution
and sensitivity will also be exceptional following the use of the Image
Bandpass Filter invented by the Turner group.
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The 1991 Kratos
Photoelectron Spectromicroscope. |
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