First Deflector Analyser Preserving Measurement Geometry
- 30° full cone acceptance without sample rotation
- Spin-resolved MDC without sample rotation
- Matrix element effects are avoided by keeping sample fixed
- Ensures same spot for all k//
- Improved ky accuracy (resolution better than 0.1°)
- Patented (WO2013/133739)
- Fast electronic deflection
Besides XPS and UPS, the DA30-L is especially developed for high quality ARPES measurements. Scienta Omicron´s deflector concept enables full cone angular scans in reciprocal space without sample movement. This allows electronic band structure mapping, even spin resolved, of the full surface Brillouin zone without changing measurement geometry, eliminating matrix element effects, and simplifying the interpretation of results dramatically.
With the DA30-L, we presented the world’s first hemispherical analyser using a ground-breaking deflector concept that enables angular scans in two dimensions of k-space without tilting the sample. Since the launch in 2013, the DA30-L has been rapidly accepted by the ARPES community.
Traditional ARPES analysers have an angular mode which is restricted to the angular dispersive θx direction. The detector records a 2D image of intensity for angle θx vs energy E. In such a setup, obtaining full cone measurements requires the sample to be physically rotated to probe the θy angular space. This physical movement can introduce multiple artefacts into the ARPES measurement.
Our analysers overcome these limits by using an internal deflection mode for the θy direction. With this deflection mode, the lens system projects individual slices of θx on to the analyser slit for a given θy angle. Hence, the detector of hemispherical analyser measures slices of θx vs E spectra. Recording these individual slices while changing the θy deflector angle builds a cube of reliable data containing intensity for all θx, θy, and E values.
The deflection mode enables the DA30-L to obtain these full cone measurements with an opening angle of up to ± 15° while avoiding sample rotation, making it an ideal high performance ARPES analyser.
The deflection feature is a big advantage as it allows to keep the sample in a fixed position and instead uses the deflectors to change the angular range in θy projected on to the analyser slit. This ensures the same position of the sample is probed during the whole measurement. In addition, keeping the experimental geometry fixed throughout the measurement sequence avoids matrix element effects which are caused by variations in ionisation cross section for different photon to sample angles. This allows to acquire higher quality data using the faster and more precise electronic deflection compared with mechanical sample movement. Another advantage, for some samples, is that decreased rotation requirements allow manipulators with fewer degrees of freedom to be used. This ultimately allows for lower sample temperatures to be reached.
The EXT analyser model features an extended energy range to lower kinetic energies. While a regular DA30-L is specified from 3 eV kinetic energy for angular/deflection mode, the EXT type analyser is capable of handling kinetic energies starting from as low as 0.5 eV. Achieving good performance at such low energies puts high demands on the analyser lens mechanics. Other specifications remain the same as for the DA30-L.
The DA30-L(W) includes the wide angular and deflection modes for kinetic energy ranges of lab based UV sources. It is mechanically prepared for the full deflection capabilities of the DA30-L mode, but is delivered without the electronics and software necessary for the high dispersive angular and deflection modes. The electronics and software upgrade is offered separately. The final upgrade to DA30-L can be done at customer site without removing the analyser from the system and without breaking vacuum. The upgrade concerns the computer, software, and high voltage system. Hence, this option presents an easy path to gain future access to the full DA30-L deflector concept and kinetic energy range.
The DA30-L(W) supports ±7°/±15° in angular mode and ±15° in deflection mode. The upper kinetic energy range in angular as well as deflection mode is limited to 50 eV.
High Energy Deflection
For experiments that require a higher kinetic energy range in deflection mode an upgrade is available. This upgrade includes electronics and software and extends the kinetic range of the deflection mode up to 800 eV.
< 1.8 meV FWHM
0.5 eV – 1 500 eV
± 3.5°, ± 7°, ± 15°
3 eV – 1 500 eV
3 eV – 200 eV
< 10-5 mbar
DN200CF (10” O.D.)
For full specifications and more information about product options, please do not hesitate to contact your local sales representative.
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