eTraining Introduction

Specimen Preparation

Leica Ultracut UCT

Histology

JEOL JSM-6400 SEM

Hitachi S-4700 FE-SEM

Hitachi FB-2000A FIB

Microanalysis

Veeco Dim 3000 AFM

Fluorescence Microscopes

Support

Holders

Introduction

High quality SEM imaging begins with proper specimen preparation and mounting. See Choosing the Preparation Method under Specimen Preparation. Here we are concerned with affixing the specimen to a specialized SEM holder.

Specimen holders are metal "vehicles" in which the specimen sits. A holder is used so that the specimen can be safely and conveniently inserted into the SEM and so that it sits securely on the SEM stage. Each scope uses a different specimen holder which is designed for accurate placement and control of the specimen within the chamber. Because of these differences, each holder should be handled and cleaned accordingly.

First, be aware that there are often two parts to the specimen holding procedure. One is a mount and the other is the special holder itself. Mounts are cheap and disposable after use. This is not the case with the special holders. Do not permanently attach specimens to our holders.

Consider what occurs within the SEM column/chamber. Within the SEM, beam electrons impinge on the sample. Only a small fraction of those electrons emerge from the specimen surface to be detected. Most of that current must be channeled to the instruments ground circuit. Therefore the specimen must be rigidly attached to the holder and be conductive. Several adhesives are available that will create the mechanical attachment to the holder, and conductivity can be enhanced through metal or carbon coating. This issue is handled in Specimen Coating under Specimen Preparation.

As you begin this important mounting step, consider the shape of your specimen. Is it flat, square, cylindrical, irregular? The shape will determine your choice of holder. We caution you to remember that you cannot insert a very large specimen into the SEM. Because you are examining such a small area, a large specimen is generally not needed anyway.

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