[3dem] Request for help in choosing the cryo TEM configuration

[Andrzej Żak]

Dear all,

I would like to thank you for accepting my request for admission to the 
group.

I have been dealing with electron microscopy for the last four years, 
mainly in the field of material science, but for two years I have been 
working with conventional biological samples. We are currently working 
on 20-year-old W-filament TEMs. I have been asked to check the market 
for cryo microscopes. Talos F200C and JEOL F-200 microscopes remain 
within our reach. I have a question for you about applying the second 
one in cryo techniques. We already choose TVIPS TemCam-XF416 CMOS, 
Fischione 2550 cryo holder, Vitrobot IV, Tergeo Plasma Cleaner.
Of course, we are limited by budget. We are looking for a universal 
device with the possibility of starting in cryo/tomography/spa. Current 
needs are on the border between material engineering and biology (the 
best possible resolution and use of STEM/EDS is also useful)

1) My first question is about Cold-FEG vs. Schottky FEG. Is the 
improvement of the resolution and contrast worth higher start price, 
higher prices of the maintenance and need of flashes every 8hr? Is there 
any advantage of using Cold-FEG in cryo/spa techniqies?

2) The second question is about HR polepiece vs. CR polepiece. Cryo 
polepiece offers point resolution 0,27 nm and dedicated cryo-box. High 
resolution polepiece offers point resolution 0,23 nm and classical 
anticintamination trap.
Assuming work that does not exceed the LN2 capacity of the holder, 
whether choosing a HR pole piece will significantly reduce us in the use 
of cryo techniques? Assuming the possibilities of both pole pieces, 
which of them in the future could offer a higher resolution of SPA 
reconstruction (with experienced operator)? Does contaminating cryo 
samples a significant problem for microscopes with a classic cold-trap?

I am aware that the answer to such a wide topic can be complex, but we 
want to get at least your short subjective opinion on how to improve the 
microscope configuration for our needs. Manufacturers of microscopes are 
not able to give us important advice, so I decided to ask for more 
experienced researchers.

Best regards
Andrzej Zak

Wroclaw University of Science and Technology / Poland