FOCUS PEEM

The Modular Concept

The FOCUS PEEM BA is the basic version of the PEEM instrument series. It is a bolt-on instrument which can be easily integrated in vacuum chambers. It is the heart of all extended PEEM instruments. The modular design of the PEEM allows adapting the instrument to the individual needs of the planned applications.

The integral sample stage of the IS-PEEM guarantees ultimate stability, various energy filters allow for optimum spectroscopy conditions, the position read out for the sample and aperture positioning offers e.g. fast re-allocation of small sample  features, a dedicated LHe cooled high precision 4 axis sample stage allows sample analysis at < 30 K together with eucentric sample rotation a k-space (transfer) lens allows for local ARUPS analysis with exceptional large angle acceptance of ±1.8 Å-1.

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Imaging High-Pass Energy Filter

The retarding imaging energy filter (IEF) acts as a high pass filter for the full image. Setting the energy filter to a specific electron energy facilitates element mapping with increased contrast.

The IEF is a dedicated energy filter for all applications with good photoelectron yield. The IEF effectively reduces the chromatic aberration, i.e. the energy spread of the electrons contributing to the formation of the image. This is of particular importance for chemical and magnetic imaging in synchrotron applications, where the achievable resolution is reduced due to the “unfocused” contribution of high energy electrons.

The IEF can also be used for micro spectroscopy analysis. XPS and AES spectra up to a kinetic energy of 1600 eV and with energy resolution well below 100 meV can be obtained in areas smaller than 1 μm.

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Time Of Flight Energy Filter

The Time Of Flight (TOF) imaging energy filter is ideally suited for energy filtered low intensity applications with electrons in the low kinetic energy range. Together with a time sensitive imaging Delay Line Detector (2D DLD), a dedicated drift tube and a pulsed light source, the TOF PEEM offers a unique detection system.

The detector allows true single electron counting with massive parallel detection and excellent signal to noise ratio. In addition to standard energy filtered TOF PEEM experiments the detector also allows for time dependent studies with an overall time resolution of < 250 ps.

Lower drift energies inside the drift tube allow higher energy resolution. The special design of the FOCUS PEEM allows for operation at extremely low drift energies (10 eV) while maintaining the lateral resolution of the instrument. The TOF PEEM has achieved an energy resolution of down to 50 meV. A prerequisite for any kind of TOF experiment is a pulsed light source such as pulsed lasers or synchrotrons.

The TOF detector may be retrofitted to existing FOCUS (IS-)PEEMs.

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Micro-Analyzer

The Micro-analyzer combines realtime surface microscopy with local chemical analysis using microspot electron spectroscopy (kinetic energy up to 1600 eV) at an energy resolution down to 80 meV and below. Laboratory and synchrotron sources (soft-XPS, UPS, AES) may be used.

The PEEM acts as a high performance entrance lens with variable magnification for the 50 mm hemispherical analyzer. The variable lateral resolution can be selected down to 1 μm spot size with the Iris aperture. Aberration compensated band pass filter.

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