FEI Themis Z S/TEM: STEM alignment and HAADF-STEM imaging (UPDATED)

This is an updated and corrected version (as always, filmed raw, unedited, unfiltered, uncensored, and uncut) of the previous tutorial I did covering STEM alignment and HAADF-STEM imaging using our Cs probe-corrected Themis Z S/TEM. While the essence of the previous version was correct, I ultimately felt a remake of the video was warranted (particularly with regards to STEM alignment) since I always strive to give the S/TEM community the most accurate, up to date, and useful information possible.
Join me as I work toward obtaining sub 80 pm STEM resolution at 200 kV using a PFIB-prepared Si sample (the same lamella prepared in the PFIB lamella prep video!) viewed along the B = [112] zone axis displaying dumbbells spaced 78 pm apart.
Please note that while the STEM alignment procedure is basically applicable to any type of STEM imaging, the only type of STEM imaging demonstrated here is HAADF-STEM imaging; eventually, separate videos covering ABF- and/or DPC-STEM imaging will be produced.
Thanks for watching! Please like, subscribe, and share and let me know if you have any questions or comments. Video topic requests are always welcome and appreciated; I enjoy making these videos and wish I could make them more frequently, but the demands of my job make it tough to do so; I’m in charge of 3 S/TEMs, 2 dual beam FIB/SEM systems, and 1 SEM and this keeps me very busy!
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[@adrianzavodov6745]

Amazing level of work skill with HRSTEM!

[@NicholasRudawski]

Thanks, I do what I can; it's the microscope, really; I simply push the right buttons on it!

[@stanbilly6823]

Thank u for ur nice video! I got a question about the convergence angle in stem mode. Our microscope is a titan themis 300kV. How to choose the convergence angle when we do the regular atomic resolution imaging? Do we need to make the convergence angle as large as possible to get a better resolution? like 30 mrad. By the way, we only got a 70um c2 aperture rather than 50.

[@NicholasRudawski]

Thank you; for obtaining the best possible resolution, you would want to use the value for alpha that gives the smallest possible probe. At 300 kV, this would correspond to the limit in the phase plate determined by tuning of the corrector. Normally, this can be around 25 mrad, but we usually tend to cut this down by 2 - 3 mrad to give 22 or 23 mrad, just to make sure we are within the limit of the phase plate and reducing the effects of higher order aberrations. 30 mrad is likely too large and will introduce too many higher order aberrations to the probe. If you are not familiar with what I mean regarding the "phase plate", please go check out my video on corrector tuning here (the thumbnail shows a "phase plate"): kzbin.info/www/bejne/pWTGk5qJpr2nedksi=WcdU0HWB-E7OzJd3

[@MirkaPawlyta]

Thank you very much Nick! Great source of needed knowledge. I wanted to ask what if the brightest point moves when the beam is tilted? What's the cause? How can this be corrected?

[@NicholasRudawski]

Hi Mirka; you're welcome. If the caustic spot moves when the beam is tilted, then your objective and/or C3 lens settings are incorrect. If this is the case, this is something that really should be fixed by a field service engineer because setting the default objective and C3 lens settings in nanoprobe STEM mode isn't something that can be done in the list of alignments that are normally accessible to users even at the supervisor level.

[@MirkaPawlyta]

Thank you very much. I will ask a field service engineer for help. @@NicholasRudawski

[@NicholasRudawski]

@@MirkaPawlyta good luck and I hope this gets resolved for you. Whatever happens, remember that the problem is not fixed unless the beam is stationary when you tilt it at the default C3 and objective lens settings. If a service technician tells you otherwise, he/she is incorrect (which, unfortunately, is something I have come across). The good news is that there are plenty of service people who do understand this; you just have to get your opened call in front of one of them. In our case, we ultimately had a high-level service person remote in to the system to fix this exact same problem.

[@dikkuroyroy9088]

Hi, I have learnt a lot of things about aberration corrected microscopy from your videos. If possible can you please share a video on acquisition of low-loss (plasmon) EELS spectra and plasmon map acquisition of Gold nanoparticles. We have FEI TITAN probe corrector in our lab (80-300 kV). Thank you very much for your efforts.😁😁

[@NicholasRudawski]

Hi Dikkuroy: thank you for the suggestion; this would certainly be an interesting video; I think something that is a little more basic with regards to EELS is probably better to cover first; doing plasmon mapping may necessitate the use of a monochromator (which we do have on our system) so it would be a rather involved video.

[@ueharaai3884]

Is this thermofisher tool?

[@NicholasRudawski]

Yes!

[@rayshen9739]

niubility

[@NicholasRudawski]

Ha ha, thanks; I had no idea what this meant so l just google searched it; you learn something new everyday!