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UHV electron spectrometer DCEMS
The
picture shows our UHV-compatible electron spectrometer "DCEMS". The spectrometer
is an electrostatic rotationally-symmetrical 90°-SDA (SDA: Spherical Deflecting
Analyzer). The analyzer was designed with the requirement for an energy resolution
DE/E of 2% at an electron-pass energy E of 7.3 keV, and for
a transmission of about 5% of the total solid angle 4 .
It works in the energy range of the K-conversion electrons (7.3 keV) as well as in
the energy range of the L-conversion electrons (13.6 keV). The base pressure is
usually 3 x 10-10 mbar. Inside the analyzer the trajectories of the electrons
leaving the sample have a mean diameter of 170 mm. The electrically negative
(positive) potential at the outer (inner) sphere is provided by a
microcomputer-controlled high-voltage power supply, keeping the mean radius
(optical circle) at ground potential. The electrons are detected by a channeltron.
A second channeltron is near the sample to perform ICEMS measurements.
The 14.4 keV Mössbauer-gamma quanta irradiate the sample through a UHV-sealed Be
window under an angle of 15° with respect to the horizontal specimen surface. The
sample manipulator allows x-, y-, and z-movement and rotations of the specimen. The
sample temperature can be varied between 40 and 1000 K. The UHV system is equipped
with surface-analytical facilities (LEED, RHEED, AES, residual-gas mass spectrometer,
ion-gun for surface cleaning (max. energy of Ar+-ions: 5 keV) and thin-film
evaporation and thickness control devices.
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