Scanning electron microscopes

Description

GEUS wishes to buy a variable pressure field emission gun Scanning Electron Microscope that is suitable for reservoir studies, mining, and general geosciences applications. The instrument must contain automated mineralogy analysis software suitable for loose particulate material embedded in epoxy, as well as for the analysis of minerals surrounded by neighbouring grains in polished sections, and must hold Secondary Electrons, Back Scattered-contrast Electrons, Energy Dispersive Spectrometry, Electron Back-Scatter Diffraction and Cathodoluminescense detectors. The offer should include training, documentation, and furthermore maintenance and support for 5 years. GEUS wishes to purchase a Field Emission Gun SEM instrument, which must be equipped with 2 energy dispersive spectrometry (EDS) detectors, an electron backscatter diffraction (EBSD) detector, a cathodoluminescense (CL) detector suitable for imaging, at least one backscattered electron (BSE) detector, at least one secondary electron (SE) detector. The instrument must be able to work under high- and low vacuum conditions. The instrument must have a camera to look inside the sample chamber. The detectors must fit simultaneously in the chamber without shadowing for each other. SE, BSE and EDS detectors need to function at the same working distance. The instrument must be able to automatically correct for drifting of the area of interest during imaging and analyses. The instrument must have an acceleration voltage range of at least 2-25 kV and a probe current that can reach intensities of 100nA or more. The instrument must give the possibility to view entire samples or load referenced images of those samples, and to navigate precisely (within 0.1 mm) to locations in the sample. The resolution of the images must be such that rocks can be imaged with an SE and BSE detector at 15 000 times magnification (polaroid scale) or higher on coated rock samples; and at 3 000 times magnification or higher for uncoated rock samples. The instrument must be able to contain a sample holder with at least 7 polished thin sections of c.48mm x 27mm in size or 15 polished blocks with a diameter of 25 mm. The sample stage must have full movement in X, Y, Z (> 130 mm viewing range). The samples must be able to be viewed in a complete 360 degree rotational view and the stage must allow for a tilting of at least 70 degrees towards the EBSD detector. The instrument must be offered with sound-insolation for the noise of the pump or pumps and have a form of stabilisation against vibrations. The instrument must be provided with a CL detector without an external mirror. A preview of the CL image must be visible at scanning speed (less than 2 s/frame). The minimum range of detectable wavelengths for the CL images must exceed 400-800 nm. The instrument must contain EDS detectors, with a Mn-peak width of 129eV full width at half maximum or narrower, a 30 mm2 or larger window, and an adjustable pulse processor speed/throughput rate (at least between 50-500 kcps). The EDS detector must be able to detect the presence of the element Carbon in carbon-coated rock samples in concentrations above 5 wt% while analysing at 15 kV. The instrument must have an EBSD detector with a minimum speed of 600 indexed patterns per second on a well-polished geological sample, maintaining a reasonable precision. The EDS or EBSD software must be able to combine the signal of one or both EDS detectors with the signal for the EBSD detector to give a combined interpretation of the results. The EBSD system must be delivered with a 70 degree pre-tilted sample-holder for thin sections. The tenderer offers software that is able to analyse the major and minor element composition of at least 1 200 representative grains in a polished section, with results for all elements in wt% or atom% in 2 decimals for at least 30 elements. The grains to be analysed are embedded in a matrix (epoxy), where all grains do not touch their neighbours. The SEM instrument must be offered with automated mineralogy analysis software that can be used for mineral mapping on solid rock samples. Ideally this software is able to measure the major and minor element composition of at least 1 200 representative grains that are part of a rock in which the individual grains touch their neighbours. The tenderer offers at least 7 days of teaching of the different SEM techniques: general use and maintenance of the instrument and the usages of the detectors on both a basic and advanced level. The tenderer offers a service contract for the duration of the contract that might be extendable after the end of the contract period.