[3dem] Insertion of Holder 626

[TALAVERA PEREZ Ariel]

Dear all,

I am using a Gatan 626 holder on a side entry TALOS microscope. I am 
getting problems with very frequent crystalline ice formation on the 
grids. Some times I get a mix of vitreous and crystalline water, but 
must of the time I only get crystalline water. I have been extra careful 
during sample preparation, and transferring the grind on to the holder, 
and I have done 48 hours holder bake out before insertion, but I still 
get ice on the grid.

I monitored the temperature of the holder during the insertion process, 
including 3 minutes for the Airlock pump. During those 3 minutes the 
temperature rises up to -152.2. Can this be the reason of the unwanted 
ice formation? How high can be the temperature of the holder to ensure a 
nice vitreous water?

I am also getting vacuum problems while inserting the holder. This 
process has resulted to be extremely, extremely sensitive. After the 3 
minutes Airlock pumping (I cannot give longer time because of the 
aforementioned temperature issue) as soon as I open the column port the 
vacuum either rises to 99 Log or completely crashes the column vacuum. 
This has happened with two different holders either cooled with liquid 
nitrogen or at room temperature. So, my question: Is this insertion 
process always that  picky or it can be that there is something wrong 
with the holders/Airlock pump?

Thanks a lot in advanced.

Best regards.

Ariel

-- 
Ariel TALAVERA PEREZ, PhD
Center for Microscopy and Molecular Imaging (CMMI)
Laboratory of Microscopy
Université Libre de Bruxelles
Rue Adrienne Bolland, 8
B-6041 Gosselies, Belgium
Phone +32 (0)26509866