Sample Holder and Specimen requirements

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SPECIMEN REQUIREMENTS

Introduction

The Cameca 4f and 1270 accept the same specimen holder. The specimen should be 24 - 24.5mm in diameter and less than 12mm thick. The area that can be analysed is with in 11mm of the center, although for high precison isotopic analysis this is reduced to 8mm from the center. Standard polished thin sections, as used for Electron Microprobe analysis, are ideal. Samples must be flat, polished and compatible with the ulta high vacuum of the sample chamber.

Sample dimensions

Sample Preparation

All epoxy resins degas to a greater or lesser extent and will contribute to the H background in the instrument. They should therefore be used sparingly and solid grain mounts should be as thin as possible (<5mm). Acrylic resins should not be used.

The Facility recommends the use of Epothin, SpeciFix-20 or EpoFix for SIMS analysis

Please read the page on sample preparation at the Epoxy Resins link.

Insulating samples need to be coated with a thin layer of Au (10-30nm) or C (as for electron probe analysis). Conducting epoxy resins (Ag loaded) and conducting paints (Ag DAG or Aquadag) may be used to obtain a conducting path from the sample to the specimen holder.

For certain types of work sample preparation is extremely important. Polishing compounds will contaminate the sample in Al (alumina polishing), Si (Syton polishing), B (diamond polishing compounds), Pb (Pb laps) and inevitably, Na.

Sample Photographs

Good, low magnification, reflected light photographs are essential for navigating round the sample. The inclined, reflected light optical microscope on the Cameca 4f has a 1.7mm field of view. SEM photographs maybe of use, but again these should be at a low magnification and include a secondary electron image.

Sample Holders

Several adapters have been constructed so that a wider variety of samples can be accommodated into the Cameca holders.

24mm diameter thin section or epoxy block.

20mm diameter thin Section or epoxy block.

4mm, 5mm and 1/4 inch diameter tube mounts.

6mm Ta or stainless steel mask mount.

Polished samples pressed into Indium.

Sample Preparation Techniques

Preparation of rare samples:
How to prepare Indium mounts:
How to prepare grain mounts: