Sunday, January 24, 2010

Super Exciting Microscopy (SEM)

The scanning electron microscope (SEM) is my new favorite toy. Ok fine, its not really mine, and I guess its not a toy, but I have to admit that I was just as giddy as a chile with a brand new Ticke Me Elmo (or whatever is cool these days) on Friday afternoon, when I got to play with one of these amazing tools. A light microscope is limited in resolution by its optics, but also fundamentally by the properties of light. The microscope uses light reflected off of the subject to see it and then the optics focus and magnify the image generated by that light. Basic physics proves that any object or feature that is smaller than the wavelength of visible light (380-750 nm) will not be detected by a light microscope. That is where the SEM comes in. An electron beam has a much smaller wavelength than visible light, and when it is used to scan an object the resulting image has much higher magnification than is possible with a light microscope.

The image below is the fungus Acremonium strictum.

This next image is a Stibella fungus growing on Manganese.

The next image is from the same sample (Stibella growing on Mn). I think we are looking at bacteria growing next to fungal hyphae (on the right side of the image) but I am not entirely sure. It is interesting that when looking at something familiar under a new level of magnification, it can be difficult to tell what you are actually looking at.

Below is another image of the fungus Acremonium strictum, but at lower magnification.

I am pretty sure that everyone in my group thought I was a total nerd when I excitedly exclaimed "yes!" upon hearing that one of our samples was dinoflagellates. These are some of my favorite marine plankton, and leave behind beautiful shells that accumulate in sediments and allow scientists to reconstruct past climate based on which species (or really morphotypes) are present. Here is one image that I thought was especially nice. The UFO shaped object is a dinoflagellate, but I dont know what species or type.

Here is an image from the same sample that I was able to make into a 3D image by taking a picture of the same thing on a stage tilted 3 degrees in either direction and then merged with a special program. Unfortunately unless you have 3D glasses, it wont be that exciting.

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