Pacific Views

First Time on SEM!

So today, I got to use the scanning electron microscope (SEM) for the very first time. The sample has to be dry, and metal-plated or embedded in paraffin or epoxy resin. This is because the chamber is open to the filament that generates the electron stream; any moisture will burn it out almost instantly.

As it happened, the last person to use it (and the room is rarely checked, so there's no telling when it was) left a note on the console saying that the filament seemed to have burned out. They were correct. So the first day I got to learn how to change it out, and practiced on a second because the backup aperture assembly had also been left with a burned out filament and carbon residue that needed to be polished off.

What I saw today: Two spore grains on the surface of a dried fern leaf. We discovered that dried fern leaves retain almost no other obviously interesting characteristics, even though they appear well preserved.

We'll try again with lichens, which should keep better considering that their nature is to sit out long dry spells with little ill effect. If I get any good pictures, I'll post them, but it may be a while. If the dried lichens don't work, I'm going to have to learn the paraffin or epoxy embedding techniques to use on fresh specimens.