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- Ultimate resolution of deltaE = 0.5meV
- Guaranteed resolution of FWHM = 1meV with detector current _>10pA and FWHM = 2meV with detector current _>70pA
- Two dimensional focussing electrostatic deflectors with correction of angular aberration
- Computer control of digital power supply with self optimising software
- Designed for mounting at any angle
- Dimensions of scattering chamber 45 x 70 mm
Delta 0.5 Philosophy
Presently available electron spectrometers have a theoretical resolution limit of about 1meV. It is shown that this limitation arises from the combined effect of the angular spread of the space charge limited beam, feeding the energy dispersive elements of the spectrometer and the angular aberrations of the dispersive elements. A new electrostatic dispersive device with controlled angular aberrations is described. An energy loss spectrometer built with such dispersive elements had a theoretical resolution limit of 0.3 meV, and an experimentally achieved resolution of 0.5meV.
H. Ibach, Journal of Electron Spectroscopy and Related Phenomena, 64/65 (1993) 819-823
During the past years Electron Energy Loss Spectroscopy (EELS) established as a famous technique in surface analysis (i.e. investigation of phonons of adsorbate vibrations but also of electronic transitions.) However problems in surface science physics became more complex and required a resolution of a few meV. In competition to techniques like IR-spectroscopy with resolutions of about 0.25meV the limitation of the resolution inEELS staill was about 5-7meV. Recently new developments using electron optic calculations and new energy dispersive elements improved the resolution dramatically. Additionally the progress in computer technology made the operation of the high sophisticated EELS-spectrometer much easier.
Professor Harald Ibach, Institut für Grenzflächenforschung und Vakuumphysik, KFA Julich, Germany, one of the pioneers in Electron Energy Loss Spectroscopy and one of the most experienced experts in the world in this specific field designed and developed an Ultimate Resolution Electron Energy Loss Spectrometer : UREELS, with a new generation of two dimensional focussing electrostatic energy dispersive elements which are patented and which give a resolution of 0.5meV. Additionally the detector current at a defined resolution are improved.
SPECS is manufacturing in Germany the Ultimate Resolution Electron Energy Loss Spectrometer : DELTA 0.5 under licence of KFA Julich and is distributing DELTA 0.5 worldwide.
The basic concept of the DELTA 0.5 spectrometer is a fixed stage monochromatorand a rotatable single stage analyser mounted on a DN250CF flange. DELTA 0.5/UREELS made of non magnetic materials can be mounted at any angle and is equipped with a double conetic shielding. Standard flange to sample distance is 330 mm, alternative lengths can be specified by customer.
The range of impact energy is variable from 0 to 200eV, the ramp energy extends up to 50V.
DELTA 0.5 guaranteed test performance of E = 1meV at a current _>10pA and E = 2meV at a current _>70pA is measured in the "straight through" mode, suitable bakeout and a base pressure <_ 0.1µPa is required.
The performance is guranteed for a background residual magnetic field less than 10mGauss. The digital DELTA 0.5 control unit - based on a 68322 micro processor - with 18 and 20 bit D/A converters is fully computer controlled. The self optimizing software enables the user to improve the detection current at fixed resolution automatically.
The DELTA 0.5/UREELS can be supplied as a component but also as part of a complete UHV-System for surface analysis.
Optional training courses of 1-2 week duration by SPECS specialists are available if required.
| Mounting Flange: | DN 250 CF (12" OD CF) | Magnetic Shielding: | µ-metal |
| Mounting: | At any angle | Total Length: | 480 mm at 330 mm sample distance |
| Sample potential: | floating, optional grounded sample | Weight: | 25 kg |
| Analyser Rotating Angle: | > 90° | Bakeout Temperature: | 250°C |
| Sample Position: | 330 mm (minimum) from
sealing face of mounting flange, on axis. Alternative lengths can be specified by customer. |
Scattering Chamber: | 45 x 70 mm |
| Cathode: | LaB6 | Detection: | Channel Electron Multiplier (CEM) |
| Resolution Specification: | dE = 1meV at detector current _>10pA dE = 2meV at detector current _>70pA |
| Ultimate Resolution: | E = 0.5 meV achieved |
| Power Supply: | Computer controlled, programmable, fully
digitised, self optimizing software for improving current and resolution,
primary energy and detection energy variable (standard values: 0 - 200eV for
impact energy and 1eV/50eV scan range (switchable)). |
| Training: | 1-2 weeks training courses (optional) |
| Note: | UHV-chambers, manipulators, complete systems
are available on request - also in combination with other analytical
techniques as LEED, AES, XPS, UPS and STM. |
To obtain further information, please contact us at elsolab@actcom.co.il.
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