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MACOur ProductsAuger Spectroscopy Standards

Micro-Analysis Consultants Ltd. has developed multi-element blocks of reference materials suitable for the compilation of a reference library of Auger sensitivity factors when used with Auger Electron Spectroscopy (A.E.S.)

There are approximately 180 high purity single element and compound reference materials from which to choose. Most of them are synthetic materials obtained from many sources worldwide together with 31 natural minerals that are suitable for geological investigations. There are also 56 standards to choose from in the MBH/NIST/BAS-EURO section of the materials selection.

A carefully selected range of elements or compounds will enable the surface analyst to compile a valuable reference library of spectra for those materials of specific interest to his field of study. A.E.S. is of particular value in the investigation of the surface chemistry of electronics materials, so we have put together an Electronics Materials Set containing 33 relevant reference materials.

A Faraday Cup, for the accurate measurement of specimen current, is available as an optional extra on all reference blocks.

Multi-element blocks containing up to 50 reference materials can be made to suit the configuration of most instruments, but the actual number of materials and the shape and size of the reference block is determined by the physical limitations imposed by the specimen holder and chamber. The reference materials each have an exposed area about 2mm².

Each block of reference materials is made from AISI 304 grade austenitic stainless steel, set with elements and compounds of your choice and polished to a ¼ micron diamond finish. All blocks are supplied with certificates of analysis and a map showing the locations of the reference materials.

The design of the reference blocks for A.E.S. is based upon that used for the production of our already established range of electron probe x-ray microanalysis (E.P.M.A.) standards blocks. For surface analysis in ultra-high vacuum (U.H.V.) environments, the design of the A.E.S. blocks has three significant differences over the E.P.M.A. blocks:

• For E.P.M.A. the reference standards are set into drilled brass blocks. However, for U.H.V. work, the brass would outgas, so non-magnetic stainless steel is used for the A.E.S. reference blocks.
• There is no coating of electrically conductive carbon on the A.E.S. blocks. For E.P.M.A. work, this coating is needed to neutralise any electron beam induced charge.
• E.P.M.A. standards are mounted using epoxy resin, which would rapidly out gas under U.H.V. conditions. The A.E.S. reference blocks are set with Wood's Fusible Metal. This is an alloy of bismuth, lead, tin and cadmium.

Wood's Metal, being electrically conductive, also serves as an electrical connection between the reference material and the stainless steel block thereby dissipating any electrical charge. However, some of the reference materials are electrical insulators, so these must be charge neutralised using a high specimen tilt angle or a lower primary beam accelerating potential.

WARNING
The block of reference materials should not be baked prior to analysis. Wood's Metal melts at about 70° C and also, because of its high vapour pressure, cadmium vapour would be liberated into the specimen chamber.