STATION 3.3NOT AVAILABLE
TGM

Description

A general purpose beamline without a fixed endstation. Generally used for photoelectron spectroscopy.

Using the Beamline

This station is currently unsupported and is used for commissioning of equipment and in-house tests. If you wish to use this beamline, then please contact the station manager.

Functional Description

Station 3.3 comprises a Toroidal Grating Monochromator (TGM) plus control and data acquisition systems. The monochromator can be used between 10 eV and 120 eV with an achievable resolving power of 1000. The energy range is covered using two gratings interchangeable while the TGM is at high vacuum. The beamline is also a good source of circularly polarized light.

Technical Description

The station consists of a toroidal grating monochromator (TGM) and its associated control electronics. The TGM itself utilises 3 optical elements, an horizontally focusing mirror, a vertically focusing mirror and (interchangeable) toroidal gratings. Additionally there are entrance and exit slits and several aperture limiting masks. The exit slits and sevvable horizontally by ± 10 cm in order to focus the instrument exactly at a particular photon energy if particularly high resolution is required. A Pyrex capillary of either 1 mm or 2 mm internal diameter is used to transfer the radiation from the exit slit to the experiment.

Details of the Mirrors and gratings available are given below. The energy range and peak energy are 'typical' values found under normal operating conditions i.e. with a capillary transferring the monochromator output to an experimental chamber. As the length and diameter of the capillary is changed for each individual experiment these figures should be viewed as guides only. Other important properties of the monochromator output are polarisation and higher order contamination. Measurements of these can be found in the station manual. Filters are available to reduce the higher order contamination.

M6.5 (Mirror)

Base material - Silicon Carbide,
Coating - Platinum
Focusing properties - 2:1 Horizontal demagnification
Included Angle - 170°

M6.5 (Mirror)

Base material - Fused Silica
Coating - Platinum
Focusing properties - 4:1 Vertical demagnification
Included Angle - 155°

LEG (Grating)

Base material - Fused Silica
Coating - Platinum
Focusing properties - Toroidal Focusing
Included Angle - 155°

HEG (Grating)

Base material - Fused Silica
Coating - Platinum
Focusing properties - Toroidal Focusing
Included Angle - 155°

LEG (Grating)

Line Density - 710 l/mm
Energy Range - 15 eV to 45 eV
Peak Energy - 24 eV
Benchmarks (Current and Energy) - 6 nA (20 eV - 30 eV)

HEG (Grating)

Line Density - 2400 l/mm
Energy Range - 40 eV to 150 eV
Peak Energy - 90 eV
Benchmarks (Current and Energy - )1.5 nA (80 eV - 110 eV)

Benchmarks

The benchmark figures are measurements taken under standard conditions. Specifically no capillary is used, the entrance and exit slits of the TGM are both set to '5.0' and the drain current from an Al2O3 photodiode (biased at -27 V) is measured across the entire range of the monochromator. The notation 8 nA (20 eV - 30 eV) means that the station is considered to be working satisfactorily if the maximum drain current is greater than 8 nA per 100 mA circulating current in the SRS and if the peak output occurs between 20 eV and 30 eV.

See Station Manual »