EM - Aperture Cleaning

Aperture Cleaning using Flamer

The following method is for cleaning platinum apertures; clean tungsten and molybdenum apertures by heating in vacuum.

Pre-clean apertures by storing them for a while in a strong solvent such as chloroform.

1. Place aperture disc in cup or hang strip from hook on cup.
2. Turn Bunsen burner to low (small blue flame).
3. Hold apertures on flamer 12mm - 20mm above aperture.
4. Adjust heat if required to turn aperture bright red. No more than 5 seconds.  Greater heat and long (more than a few seconds) flaming times increase crystalinity of the disk or strip and eventually ruin the apertures.
5. Inspect aperture on a microslide with a microscope. Repeat heating if required.

Note: the force of the heat, rather than the flame itself, cleans the aperture.

Cleaning MAP Apertures

When mounting Pt or Mo apertures, please note:

Very small and loose particles may contaminate new and well made apertures. Inspect aperture, after placing it flat side up on a clean watch glass. Use a light microscope with a 10 to 40 x objective.

If required, ultra-sonicate aperture in absolute alcohol and blot, flat side up on filter paper. Work with aperture container and electron microscope holder above lint free material, such as aluminium foil or a large filter paper.

Use tweezers, exerting little pressure, and lift aperture straight into aperture holder.