[3dem] Image distortion issues

[William Nicolas]

Hello everyone,

I am actually having trouble with coating my grids with gold particles to use as fiducial markers prior to tilt series acquisition.

I usually use outdated secondary antibodies linked to 5nm gold particles but it went out. I thus bought a gold particle solution from BBI solution and can’t get the parameters straight.
I tested different concentrations and different ways to put them on my grid and have found optimal settings. 

The problem is now that I want to use them on 200nm thick HM20 embedded sample slices which are deposited on a slot-grid coated with formvar, I have  distorted images on the camera BUT not on the fluorescent screen.
The beads and image seems to be stretched in one direction and it is not astigmatism nor sample drifting. I thought of charges building up on the surface of the sample, distorting the electrons that are transmitted, maybe because of the BBI solutions liquid media…

Do you have a solution to prevent charges from building up on the surface of my sample ?

Thanks in advance.

Regards,

William Nicolas, PhD student, CNRS UMR 5200