[3dem] FEI-VPP phase change to opposite direction

Danev, Radostin danev at biochem.mpg.de
Thu Jan 26 09:29:09 PST 2017

Hi Jian,

If the CTF rings are moving outwards (make sure you are underfocus!) that means positive charging. The reason is most probably contamination on the phase plate film. If the heater is working properly (voltage ~ 4.0V, current ~ 25 mA) then the contamination is pre-existing, deposited during manufacturing, transport or handling of the phase plate. Are all VPP slots showing the same behavior?



From: 3dem [3dem-bounces at ncmir.ucsd.edu] on behalf of Sacha De Carlo [sacha.decarlo at dectris.com]
Sent: Thursday, January 26, 2017 8:32 AM
To: jamon
Cc: 3dem at ncmir.ucsd.edu
Subject: Re: [3dem] FEI-VPP phase change to opposite direction

Could it be that the holder, with the new VPP, is no longer sitting in the back focal plane, where it should be?
In any case, these are things to check with you FEI service engineer.

All the best,

On Thu, Jan 26, 2017 at 6:11 AM, jamon <jamonshi at gmail.com<mailto:jamonshi at gmail.com>> wrote:
Dear Lister,

We just changed our FEI Volta Phase Plate on Krios. But after activation, the phase changed to opposite direction, the FFT rings moves outward instead of inwards as it should be. The gold particles all looks all white as if in overfocus. I had never seen such behavior with previous two VPPs we had. Did anybody have similar experience? Thanks in advance.

Best Regards,
Jian SHI
Manager, Cryo Electron Microscopy Facility
Center for BioImaging Science
National University of Singapore

3dem mailing list
3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>

Sacha De Carlo, Ph.D.
Business Development Manager EM
Phone: +41 56 500 2190 | Mobile: +41 79 354 4740 | Email: sacha.decarlo at dectris.com<mailto:sacha.decarlo at dectris.com>
DECTRIS Ltd. | Taefernweg 1 | 5405 Baden-Daettwil | Switzerland | www.dectris.com<https://www.dectris.com>

 [facebook] <https://www.facebook.com/pages/Dectris-Ltd/623855944369304>  [https://www.dectris.com/tl_files/root/signatur/twitter-ico1.png] <https://twitter.com/DECTRIS_News>


Confidentiality Note: This message is intended only for the use of the named
recipient(s) and may contain confidential and/or privileged information. If you
are not the intended recipient, please contact the sender and delete the message.
Any unauthorized use of the information contained in this message is prohibited.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ncmir.ucsd.edu/pipermail/3dem/attachments/20170126/c475f52f/attachment-0001.html>

More information about the 3dem mailing list