4/4/97


Hi All,

We are interested in obtaining a carbon coated grid but in a "butterfly" or

folding configuration instead of a single grid. We have some powders that are

radioactive and though our microscope (TEM) is already contaminated we would

like to reduce the potential for further contamination. I was thinking that a

butterfly grid with carbon on both sides may help.

Any thoughts? Does anyone sell such a beast? Any other ideas for reducing the

amount of particles that may come off?

Most of my work is with metal samples and I haven't worked with carbon coated

grids much. Can we make something like that easily? I saw the discussions

about holey carbon films but that is not quite what we are after!

TIA

John Vetrano

Pacific Northwest National Laboratory

Richland, WA 99352

js_vetrano@pnl.gov


A formvar or collodion film could work--especially if charging is

not a problem. You don't say whether the sample is conductive or not.

William Tivol

tivol@wadsworth.org


John

If I understand your question correctly, I think that you have several

options.

1) You could make your own carbon coated folding grids using the same

procedures used for single grids ( check for example "Techniques for

Electron Microscopy" Ed. Desmond Kay ). The techniques (there are a number

of them) are relatively simple.

2) Could you use a single carbon coated grid and then deposit carbon (by

vacuum evaporation) on top of your particles on the grid ?. This would

serve the same purpose as the carbon coated folding grids. You might end

up contaminating your evaporator however.

No matter what you do, you will still run the risk of contaminating your

scope since some of the film might break during observation. Also , keep

in mind that the increased thickness (two carbon layers), will decrease

your resolution. This might or might not affect the information you are

after.

Jordi Marti

MartiJ@MTOMP201.Research.Allied.com


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