[3dem] Powdered carbon fiber

[Ruben Diaz-Avalos]

Hi Terje,

At some point I was also looking at powdered crystals of peptides in the EM, and was concerned that they were not really stuck to the grid, so to have peace of mind, I evaporated a rather fine layer of carbon on top of the sample after the powder had been applied. Never saw any ill effects on the microscope, but then again, the amount was so insignificant that it was unlikely to have any discernible effect.

Of course, with time I stopped doing that with every sample and never heard Ken Taylor screaming about somebody ruining the microscope!

Ruben.

********************************************

Ruben Diaz-Avalos, Ph.D.,
Technical Director,
New York Structural Biology Center,
89 Convent Ave. at 133rd St.,
New York, NY 10027
tel: (212)939-0660 x 529
cell:(917)515-6353

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From: Terje Dokland [mailto:dokland at uab.edu]
To: 3dem at ncmir.ucsd.edu
Sent: Mon, 13 Sep 2010 14:25:22 -0400
Subject: [3dem] Powdered carbon fiber

We have a user in the materials science who is interested in looking  
  at carbon fiber samples in the TEM. My understanding is the sample  
  will be carbonized and powdered, then applied it to holey film before  
  putting it in the microscope. They are interested in the pore sizes.  
  Our F20 TEM is primarily used for cryo-EM of biological samples.  
  Should I be concerned about contaminating the column? Carbon powder  
  does not seem like something I want inside the column, but perhaps it  
  should not be a concern? As long as the powder stays on the grid it  
  should not be a problem, I suppose, but just sprinkling the powder on  
  the grid does not seem to be such a good idea. Would there be a way  
  to ensure that the sample does stick to the grid, such as washing or  
  outgassing or pre-treating the grids?
  
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