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<font face="Arial">Dear <font face="Arial">Colleagues<br>
<font face="Arial">Plasma cleaning is self-explanatory - well,
it is cleaning by plasma, sometime using a dedicated <font
face="Arial">device. Plasma cleaning requires normally high<font
face="Arial"> energy plasma, which prod<font face="Arial">uced
using high-frequency generator (microwave?). Most modern
"plasma cleaners" do not use high-voltage to generate
plasma.<br>
<br>
<font face="Arial">"Glow discharge" i<font face="Arial">s
more tricky. Historically, glow discharge was
performed to mitigate hydrop<font face="Arial">hobic
properties of carbon.Often, home-made
"glow-discharge" units were used. Such unit
usually constructed using<font face="Arial"> </font>mechanical
pump, some sort of "bell-jar,"<font face="Arial">
</font>high-voltage po<font face="Arial">w</font>er
supply and discharge electrodes. Residual air <font
face="Arial">was</font> used to generate a
plasma. Such units are simple, but results
sometime inconsistent. "Plasma cleaning" units at
low power settings can be used for more
reproducible "glow-discharge." <br>
<br>
<font face="Arial">On <font face="Arial">philosophical</font>
note, speaking about "glow-discharge" ... I
never was able to understand how electro-c<font
face="Arial">onductive carbon can hold a
"charge"<font face="Arial">? My personal
theory is that common "carbon" is
contaminated by oil from dirty oil-based
vacuum-evaporators. <font face="Arial">"Glow
discharge" essentially ionizes residual
oil. <font face="Arial">Oil within the
carbon <font face="Arial">prod<font
face="Arial">uces many bad effects
on carbon: oil can oxidize (carbon
aging); oil can decompose for
different reasons; oil <font
face="Arial">destabilizes</font>
carbon under e-beam etc. From this
(my personal) prospective, "glow
discharge" has limited beneficial
effect on pure, clean carbon<font
face="Arial">. In fact, I am using
pure, clean (oil-free) ultrathin
carbon for EM for decades. This
carbon is <font face="Arial">remarkable</font>
stable under the beam and survived
freezing etc. It also ha<font
face="Arial">s very low
background noi<font face="Arial">s</font>e
because it is not "etched" by
"glow discharge."</font></font></font></font></font></font></font></font></font><br>
</font></font></font></font></font></font></font></font><br>
<font face="Arial">Sergey<br>
<br>
</font></font>
<div class="moz-cite-prefix">On 9/20/2016 11:46 AM, Mike Strauss
wrote:<br>
</div>
<blockquote
cite="mid:CAD7od6VkGEbs8HHg6GxCjUmNh3B0457rNwq+Y+JWoXEgenM0YQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hi Sergej,
<div><br>
</div>
<div>Just a reminder, because I'm sure you are aware, but there
are other factors besides the vacuum that affect the results
of the glow discharger (or plasma cleaner in your case).
These include: distance between electrodes, voltage applied
across electrodes, shape of electrodes, nature of carrier
(the thing your grids are on), type of residual gas in
chamber.</div>
<div><br>
</div>
<div>I have always assumed that the name of the instrument
depends on its intended use. So a glow discharger becomes a
plasma cleaner when you leave it on too long and burn off all
the carbon. </div>
<div><br>
</div>
<div>mike</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Sep 20, 2016 at 7:03 PM, Sergej
Masich <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:Sergej.Masich@ki.se" target="_blank">Sergej.Masich@ki.se</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word">
<div>
<p class="MsoNormal"><span lang="EN-GB">Dear List, dear
</span>Benoît,</p>
<p class="MsoNormal">I have some different experience
that can be wrong though. A colleague and a good
friend of mine from Albuquerque successfully used his
plasma cleaner to glow-discharge carbon films. I
decided to copy his settings in our Lab and ordered
the same model. However, that model could not be sold
to European customers due to some regulations. I
purchased more expensive model from the same supplier.
It did not work! As the result of “glow discharge”, I
got empty grids, no traces of carbon. To make a long
story short, we installed a needle valve and a gauge
to control the vacuum degree. We got hydrophilic
carbon at poorer vacuum and no carbon at better
vacuum. Since then, I used the plasma cleaner for many
years to prepare hydrophilic carbon surface.</p>
<p class="MsoNormal">In my opinion, this also makes
sense. The ions in plasma have longer free path at
higher vacuum. As the result, they have higher energy
that can result in more efficient removal of the
“dirt” from the surface.</p>
<p class="MsoNormal">I never read any confirmation of my
“theory” that can be completely wrong but I hope it
will contribute to the discussion.</p>
<p class="MsoNormal">Sincerely,</p>
<div>Sergej Masich</div>
<p class="MsoNormal">=============================<br>
Dr. Sergej Masich<br>
Dept. of Cell and Molecular Biology<br>
Karolinska Institutet<br>
Box 285<br>
171 77 Stockholm, Sweden<br>
tel: <a moz-do-not-send="true"
href="tel:%28%2B%2946%20-%208%20-%20524%20873%2061"
value="+46852487361" target="_blank">(+)46 - 8 - 524
873 61</a><br>
mobile: (+)46 - 736 - 833 693<br>
e-mail: <a moz-do-not-send="true"
href="mailto:Sergej.Masich@ki.se" target="_blank">Sergej.Masich@ki.se</a><br>
</p>
</div>
<div>
<div class="h5">
<br>
<div>
<div>On 20 Sep 2016, at 18:33, <<a
moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a>>
<<a moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a>>
wrote:</div>
<br>
<blockquote type="cite">
<div
style="font-size:12px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">Hi
David,<br>
<br>
This could be right. However I doubt it. Within
20 to 30 minutes we can completely disintegrate
the carbon of quantifoil grids with the glow
discharge machine set so that it glows strongly
without sparkling.<br>
<br>
Cheers<br>
Ben<br>
<br>
______________________________<wbr>__________<br>
Von: Morgan, David Gene [<a
moz-do-not-send="true"
href="mailto:dagmorga@indiana.edu"
target="_blank">dagmorga@indiana.edu</a>]<br>
Gesendet: Dienstag, 20. September 2016 18:12<br>
An: Zuber, Benoît (ANA);<span> </span><a
moz-do-not-send="true"
href="mailto:3dem@ncmir.ucsd.edu"
target="_blank">3dem@ncmir.ucsd.edu</a><br>
Betreff: Re: glow discharge vs plasma cleaning<br>
<br>
Ben,<br>
<br>
<br>
Maybe someone else on the list can shed some
light on this, but I don't know whether the
strength of the plasma created in an EM "glow
discharge device" is comparable to that of what
is called a "plasma cleaner." I suspect not,
but could be wrong.<br>
<br>
<br>
That said, over zealous use of a plasma
cleaner can remove _all_ the carbon from an EM
grid (I have done this with a lacy carbon grid),
so having too much power can be a bad thing...<br>
<br>
<br>
--<br>
David Gene Morgan<br>
Electron Microscopy Center<br>
047D Simon Hall<br>
IU Bloomington<br>
<a moz-do-not-send="true"
href="tel:812%20856%201457"
value="+18128561457" target="_blank">812 856
1457</a> (office)<br>
<a moz-do-not-send="true"
href="tel:812%20856%203221"
value="+18128563221" target="_blank">812 856
3221</a> (3200)<br>
<a moz-do-not-send="true"
href="http://iubemcenter.indiana.edu"
target="_blank">http://iubemcenter.<wbr>indiana.edu</a><br>
______________________________<wbr>__<br>
From: <a moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a>
<<a moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a>><br>
Sent: Tuesday, September 20, 2016 12:06 PM<br>
To: Morgan, David Gene; <a
moz-do-not-send="true"
href="mailto:3dem@ncmir.ucsd.edu"
target="_blank">3dem@ncmir.ucsd.edu</a><br>
Subject: Re: glow discharge vs plasma cleaning<br>
<br>
Hi David and Luiza,<br>
<br>
Many thanks for the explanations. OK this «
makes sense ». But it is a shame that people use
two different words for the same thing (good job
from the marketing team though ! ). It would be
much better to use only one term and then give
specific gaz conditions. So many people are
convinced that glow discharge and plasma
cleaning are two different things and that you
need two different machines.<br>
We have a so-called glow discharge machine from
defunct Balzers. It still functions perfectly
well, it looks like what people describe as a
glow discharge machine : a glass cylinder with
two metal plates below and on top, and it has an
needle-valve inlet. We typically let the inlet
in contact with the air and let a tiny bit of
air flow in to get a constant pressure in the
chamber and thereby have a reproducible
procedure. We can quite precisely control the
pressure that we want inside. However if we want
to use whatever gas mixture instead of good old
nitrogen and oxygen, we can just buy and connect
the relevant gas bottle(s). No need to purchase
a new machine.<br>
If I listened to what so many people told me, I
would have long bought another machine, which
would probably have been a waste of money and
lab space. I think people should be more aware
of this before spending their (tax payer ?)
money.<br>
<br>
Cheers<br>
Benoît<br>
<br>
<br>
De : "Morgan, David Gene" <<a
moz-do-not-send="true"
href="mailto:dagmorga@indiana.edu"
target="_blank">dagmorga@indiana.edu</a>><br>
Date : mardi, 20 septembre 2016 17:51<br>
À : Benoit Zuber <<a moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a>><br>
Objet : Re: glow discharge vs plasma cleaning<br>
<br>
<br>
Ben,<br>
<br>
<br>
<br>
They are technically the same thing _except_
that in common EM usage, "glow discharge" is
done using ambient gases (i.e., you just pull a
modest vacuum and create a plasma) while "plasma
cleaning" is done using a specific mix of gases
(Ar, O and with the Gatan device H) instead of
ambient gases (i.e., you flush the chamber with
specific gases, then pull the vacuum and create
the plasma).<br>
<br>
<br>
<br>
With more O in the plasma, the cleaning tends
to be stronger (burns more material in the
sample) and the Ar/O mix prevents side reactions
that can be caused by the abundant N in the
atmosphere.<br>
<br>
<br>
--<br>
David Gene Morgan<br>
Electron Microscopy Center<br>
047D Simon Hall<br>
IU Bloomington<br>
<a moz-do-not-send="true"
href="tel:812%20856%201457"
value="+18128561457" target="_blank">812 856
1457</a> (office)<br>
<a moz-do-not-send="true"
href="tel:812%20856%203221"
value="+18128563221" target="_blank">812 856
3221</a> (3200)<br>
<a moz-do-not-send="true"
href="http://iubemcenter.indiana.edu"
target="_blank">http://iubemcenter.<wbr>indiana.edu</a><br>
______________________________<wbr>__<br>
From: 3dem <<a moz-do-not-send="true"
href="mailto:3dem-bounces@ncmir.ucsd.edu"
target="_blank">3dem-bounces@ncmir.ucsd.edu</a>>
on behalf of<span> </span><a
moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a><span> </span><<a
moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank"><wbr>benoit.zuber@ana.unibe.ch</a>><br>
Sent: Tuesday, September 20, 2016 11:28 AM<br>
To:<span> </span><a moz-do-not-send="true"
href="mailto:3dem@ncmir.ucsd.edu"
target="_blank">3dem@ncmir.ucsd.edu</a><br>
Subject: [3dem] glow discharge vs plasma
cleaning<br>
<br>
Dear colleagues,<br>
<br>
I often hear people saying: „Did you treat your
grid with glow discharge or with plasma
cleaner?” Or : ”It is absolutely essential for
application XY to pretreat the grid with a
plasma cleaner and not by glow discharge!”.<br>
<br>
Can anyone explain what the difference between
glow discharge and a plasma cleaning is?<br>
<br>
According to Wikipedia, this is the same thing (<a
moz-do-not-send="true"
href="https://en.wikipedia.org/wiki/Glow_discharge"
target="_blank">https://en.wikipedia.org/<wbr>wiki/Glow_discharge</a>).
The page starts with this sentence:<br>
“A glow discharge is a plasma<<a
moz-do-not-send="true"
href="https://en.wikipedia.org/wiki/Plasma_%28physics%29"
target="_blank">https://en.wikipedia.<wbr>org/wiki/Plasma_(physics)</a>>
formed by the passage of electric current<<a
moz-do-not-send="true"
href="https://en.wikipedia.org/wiki/Electric_current"
target="_blank">https://en.wikipedia.<wbr>org/wiki/Electric_current</a>>
through a low-pressure gas”<br>
<br>
I look forward to an interesting debate.<br>
Ben<br>
<br>
Prof. Benoît Zuber<br>
Institute of Anatomy<br>
University of Bern<br>
Baltzerstrasse 2<br>
Postfach 922<br>
3000 Bern 9<br>
Switzerland<br>
Tel. <a moz-do-not-send="true"
href="tel:%2B41%2031%20631%2084%2040"
value="+41316318440" target="_blank">+41 31
631 84 40</a><br>
<a moz-do-not-send="true"
href="mailto:benoit.zuber@ana.unibe.ch"
target="_blank">benoit.zuber@ana.unibe.ch</a><br>
<a moz-do-not-send="true"
href="http://www.ana.unibe.ch/%7Eexmo/"
target="_blank">http://www.ana.unibe.ch/~exmo/</a><br>
<br>
______________________________<wbr>_________________<br>
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href="https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem"
target="_blank">https://mail.ncmir.ucsd.edu/<wbr>mailman/listinfo/3dem</a></div>
</blockquote>
</div>
<br>
<div><br>
<br>
</div>
<br>
</div>
</div>
</div>
<br>
______________________________<wbr>_________________<br>
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</blockquote>
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<pre class="moz-signature" cols="72">--
--------------------------------------------
Sergey Ryazantsev Ph.D.
Phone: 310-453-0748
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:sryazant@ucla.edu">sryazant@ucla.edu</a></pre>
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