[3dem] DDD on 120kV TEM equipped with LaB6

[Henning Stahlberg]

Dear Benjamin,
If you would have gone to much more defocussed C2, a small C2 aperture, and therefore darker illumination, better coherence and longer exposure time, you should have been able to get many more Thon rings and much higher resolution also with the LaB6 source.

An interesting question is:

For what type of electron microscope, kV,  detector, purchasing price, maintenance costs, and operator workload is the ratio of “number of atomic structures produced in a week” and “overall facility cost” maximal?

Henning.

Henning Stahlberg
henning.stahlberg at icloud.com<mailto:henning.stahlberg at icloud.com>
http://c-cina.org
Tel.: +41 79 502 75 22
(sent from a mobile device)

On Mar 21, 2019, at 22:20, Benjamin Bammes <bbammes at directelectron.com<mailto:bbammes at directelectron.com>> wrote:

Hi Mohammad,

I collected some cryo-EM data with a DE-12 on a LaB6 120 kV TEM a couple years ago (see attached slides). Using about 60 images collected in less than an hour, I got a 10 Angstrom reconstruction of Mm-Cpn. The combination of the high SNR of the DE-12 and it's high speed for doing motion correction seemed to make a big difference (note that very few 120 kV LaB6 reconstructions at that time had reached 15 Angstroms resolution, let alone 10). I've always been interested to see if someone could push this further, since we clearly saw Thon rings up to 6 Angstroms or so. So I think this is quite promising, providing the direct detector has sufficient dynamic range for lower energy electrons and high-speed dose fractionation for motion correction on these less stable instruments.

Note that the DE-12 camera has since been updated and is now the DE-DirectView.

(Acknowledgment to Wah Chiu who was our collaborator on this short proof-of-concept experiment.)

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On Thu, Mar 21, 2019 at 9:01 AM Mazhab-Jafari, Mohammad <Mohammad.Mazhab-Jafari at uhnresearch.ca<mailto:Mohammad.Mazhab-Jafari at uhnresearch.ca>> wrote:
Dear 3DEM community,

I would like to know if anyone has used a K2 or any other direct detector device cameras on a 120kV TEM equipped with a LaB6 emitter? If so what resolution range can be expected for 3D reconstruction of a well-behaved protein (~1MDa in size) with single particle image analysis method?

Any insights will be appreciated.

Kind regards,
Mohammad.


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Mohammad Mazhab-Jafari, Ph.D.
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