The ARL SEMQ microprobe

Description: The SEMQ in MTM is a microprobe from ARL upgraded with modern analytical software for wavelength dispersive analyses.  This micro analytical tool for qualitative analyses can also treat polished samples quantitatively using reference materials of known composition. The SEMQ was in the early 80’s the most advanced instrument for microprobe analysis capable of handling six X-ray spectrometers.  Each wavelength dispersive spectrometer provides an option between two analysing crystals and works at a take-off angle of 52.5° at minimal X-ray absorption.  The overall design was so well considered that even nowadays this instrument is still used on several locations all over the world.  Most of them are upgraded in order to be competitive with the presently made microprobes. A focused electron beam of high energy electrons irradiates a micron sized superficial volume in a chosen zone of the polished specimen generating secondary electrons, backscattered electrons, absorbed electrons and moreover X-rays.  The characteristic X-rays emitted by the elements present in this zone can be analysed either based on their energy with the energy dispersive spectrometer or based on their wavelength with the wavelength dispersive spectrometers.  The images with the secondary or backscattered electrons can be used to visualize the position of the chosen analysis spots.  The current of the electron beam is always monitored to compensate for beam changes during short analyses.  A beam stabilisation unit can be activated moreover especially in case of long term acquisition.

Technical details:
Supplier: ARL (Applied Research Laboratories) Type: SEMQ Year of construction: 1976 Serial number: 34
The electron microscope:
Thermionic electron gun with tungsten hairpin filament Accelerating voltage: 1 – 30 kV in 1 kV steps Probe current: 0.5 nA – 15 µA Working distance 1.5 - 3.0 mm Secondary electron detector Backscattered electron detector Absorbed electron / Beam current microampere meter Optical microscope Specimen size: polished samples of 1” (25.4 mm) or 1 ¼” (31.8 mm) diameter, up to 2 cm height Programmable XYZ stage for five 1” or four 1 ¼” samples together
The energy dispersive spectrometer:
10 mm2 Si- Li doped X-ray detector with beryllium window Resolution: 154 eV Take off angle: 52.5° Analysable elements: Na to U Analytical software from EDAX
The wavelength dispersive spectrometers:
Five spectrometers with analysing crystals: LiF/ADP, LiF/PET, LiF/ADP, LiF/PET, OV95/TAP 1 Gas flow proportional counter & 4 Gas filled proportional counters Rowland circle: 127 mm Take off angle: 52.5° Analysable elements: B to U Analytical software from Advanced Microbeam Incorporation

Room: 91.04

More Technical information: Techinfo@mtm.kuleuven.be

 

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