[3dem] (mean Inner potential) Re: 3dem Digest, Vol 142, Issue 38
Philip Köck
philip.koeck at ki.se
Tue Jun 18 00:26:46 PDT 2019
Thanks for the reference.
I can't make sense of a thickness-independent contribution to the phase shift either. The way I see it even a surface layer of dipoles would lead to a constant MIP and a phase shift proportional to the thickness.
One can think of a simple model: A slab of completely neutral material (made of neutrons) covered in a layer of positive charge and outside that a layer of negative charge that balances the positive charge. The potential inside this slab will be constant and independent of the thickness of the slab.
I wonder if we can get a comment from someone who knows more.
All the best,
Philip
________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Benjamin Himes <himes.benjamin at gmail.com>
Sent: Monday, 17 June 2019 20:45:48
To: 3dem at ncmir.ucsd.edu
Subject: [3dem] (mean Inner potential) Re: 3dem Digest, Vol 142, Issue 38
Hi Philip,
The mean inner potential (MIP) refers to a total "interaction" potential that is considered a material property. It consists of all the sources contributing to the potential well seen by an imaging electron, including those you suggest (nuclear and electronic contributions.)
Yes, physical changes to the surface via adsorbed matter will directly affect the MIP. I believe the working hypothesis for the source of the "Volta" potential is through heat/exposure related modification of surface adsorbates.
It is also interesting to note that in addition to the electronic character of the object, the surface contributions of adsorbates and heating, there is another thickness independent phase shift (at least for carbon) the source of which I am not clear on. Happy to hear an explanation from anyone in the know : )
Please have a look at this paper where all of the non-Volta contributions are discussed and also measured.
"Electron holography of thin amorphous carbon films: Measurement of the mean inner potential and a thickness-independent phase shift"
doi: j.ultramic.2005.10.004
HTH
Ben
------------------------
Benjamin Himes
cryoEM methods development
Grigorieff lab<https://mail.hhmi.org/owa/redir.aspx?C=SbsCefkcbOt75jDyr05lpd3OifVN_utmfvnhZrtXS7Bl2i2eOXXVCA..&URL=http%3a%2f%2fgrigoriefflab.janelia.org%2f>, HHMI Janelia Research Campus
cryoSTAC development @ emClarity<https://mail.hhmi.org/owa/redir.aspx?C=8yDzXj54yTidMevTB7q5m3liEVwqAZ9LxuXQ4iYOVvtl2i2eOXXVCA..&URL=https%3a%2f%2fgithub.com%2fbHimes%2femClarity%2fwiki>
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Today's Topics:
1. mean inner potential of a solid (Philip K?ck)
2. NYC Computational Cryo-EM Summer Workshop
(Cindy Rampersad-Phillips)
3. side entry holder for autogrids? (Michael Elbaum)
4. Re: side entry holder for autogrids? (Wim Hagen)
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Message: 1
Date: Mon, 17 Jun 2019 08:27:35 +0000
From: Philip K?ck <philip.koeck at ki.se<mailto:philip.koeck at ki.se>>
To: "3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>" <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>,
"microscopy at microscopy.com<mailto:microscopy at microscopy.com>" <microscopy at microscopy.com<mailto:microscopy at microscopy.com>>
Subject: [3dem] mean inner potential of a solid
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Hi all.
I've been wondering what the mean inner electrostatic potential of a solid (for example the 10 V of carbon) is actually due to.
Is it purely caused by the distribution of nuclei and electrons in the solid itself or could there be a contribution from adsorbed surface charges?
All the best,
Philip
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Message: 2
Date: Mon, 17 Jun 2019 10:46:34 -0400
From: Cindy Rampersad-Phillips <crampersad at flatironinstitute.org<mailto:crampersad at flatironinstitute.org>>
To: 3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>
Subject: [3dem] NYC Computational Cryo-EM Summer Workshop
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Dear 3D-EM group,
We are organizing a 2-day workshop on "Computational Cryo-EM" which will
take place at the Flatiron Institute, Simons Foundation, in New York City,
on August 8-9, 2019. This summer workshop revives a tradition started by
Joachim Frank and Gabor Herman many years ago. The topics will include:
advances in reconstruction algorithms, software implementations and
automation, motion correction, 2D/3D classification and continuous
heterogeneity analysis, and related mathematical results and new problems.
There will be 16 speakers in total, each giving 30-minute talks, in a
workshop setting which promotes the open exchange of ideas. In addition,
there will be a poster session.
For more information, including the list of confirmed speakers, see the
event website:
https://www.simonsfoundation.org/event/nyc-computational-cryo-em-summer-workshop/
To apply, please fill in the following registration form:
https://indico.flatironinstitute.org/e/CryoEM
Registration will be closed once we reach capacity, so please register soon
to guarantee your attendance.
On behalf of the organizing committee,
Joakim And?n (Flatiron)
Alex Barnett (Flatiron)
Leslie Greengard (Flatiron / NYU)
Roy Lederman (Yale)
Amit Singer (Princeton)
Marina Spivak (Flatiron)
Regards,
Cindy
--
Cindy Rampersad-Phillips
Coordinator, Center for Computational Mathematics
*Flatiron Institute*
162 Fifth Ave
<https://www.google.com/maps/place/Flatiron+Institute/@40.7405662,-73.9907621,15z/data=!4m5!3m4!1s0x0:0x8849799a20fe5d4a!8m2!3d40.7405662!4d-73.9907621>
New York, NY 10010
<https://www.google.com/maps/place/Flatiron+Institute/@40.7405662,-73.9907621,15z/data=!4m5!3m4!1s0x0:0x8849799a20fe5d4a!8m2!3d40.7405662!4d-73.9907621>
646.603.3750 *main*
646.603.3718 *direct *
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Message: 3
Date: Mon, 17 Jun 2019 16:00:45 +0000
From: Michael Elbaum <michael.elbaum at weizmann.ac.il<mailto:michael.elbaum at weizmann.ac.il>>
To: "3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>" <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>
Subject: [3dem] side entry holder for autogrids?
Message-ID: <77389ED5A5E5A947A5FEA1B9E8D512CB01961EB25D at ibwmbx03>
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Hi all, wondering if anyone has heard/thought/dreamed of a side entry holder for clipped grids? This would be very useful in mixed company (of microscopes, of course), and could enable analysis of grids post-tomography by non-standard methods such as EDS. Perhaps someone has experience in modifying a 626 tip for the purpose?
regards,
Michael
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Message: 4
Date: Mon, 17 Jun 2019 18:16:32 +0200
From: Wim Hagen <hagen at embl.de<mailto:hagen at embl.de>>
To: "3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>" <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>
Subject: Re: [3dem] side entry holder for autogrids?
Message-ID: <44A00032-E921-429F-8BD0-03AA24FEC02A at embl.de<mailto:44A00032-E921-429F-8BD0-03AA24FEC02A at embl.de>>
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Hi Michael,
I?ve discussed this with Chris Booth from Gatan some time ago, a multiple cartridge side entry holder will for sure also help a lot of people with side-entry screening systems, preparing for later data collection in central facilities. With other people?s ideas for cheap side-entry low-kv screening tools, this could be quite a market.
Best,
Wim Hagen
EMBL Heidelberg
> On 17. Jun 2019, at 18:00, Michael Elbaum <michael.elbaum at weizmann.ac.il<mailto:michael.elbaum at weizmann.ac.il>> wrote:
>
> Hi all, wondering if anyone has heard/thought/dreamed of a side entry holder for clipped grids? This would be very useful in mixed company (of microscopes, of course), and could enable analysis of grids post-tomography by non-standard methods such as EDS. Perhaps someone has experience in modifying a 626 tip for the purpose?
> regards,
> Michael
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