Archive of ESEM Related Posts from the Microscopy Listserver
From oldest to most recent - - -Updated on 23 Mar 1998 - - - Return to PVSEM Page
View old posts from Feb. 94 to Dec. 96 - - - - -
View old posts from Mar. 97 to Sep. 97
View old posts from Nov. 97 to Mar. 98
EMs in Turkey - 29 May 1998
re: EMs in Turkey - 30 May 1998
Observation of cell cultures in ESEM - 30 Jun 1998
ESEMs and Biological Specimens - 17 Aug 1998
Re: ESEMs and Biological Specimens - 18 Aug 1998
FWD: ESEMs and Biological Specimens - 18 Aug 98
RE2: ESEMs and Biological Specimens - 19 Aug 1998
ESEM: Use of Helium Gas -- Summary - 24 Sep 1998
Re: ESEM: Use of Helium Gas -- Summary - 27 Sep 1998
Re2: ESEM: Use of Helium Gas -- Summary - 26 Sep 1998
SEM Heating stages - 21 Oct 1998
Re: SEM Heating stages - 21 Oct 1998
Re2: SEM Heating stages - 21 Oct 1998
Re[3]: SEM Heating stages - 22 Oct 1998
FEG,ESEM or LV-SEM? - 15 Dec 98
RE: FEG, ESEM or LV-SEM? +OM and SEM dont agree - 17 Dec 1998
RE: Removing gold from fossils - 14 Mar 1999
Removing gold from fossils/SE detection - 20 Mar 1999
ESEM Tensile Stage - 29 Mar 1999
Re: SEM and wood - 31 Mar 1999
Re: ESEM Tensile Stage - 31 Mar 1999
ESEM/Poor Vacuum Page
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Date: Mon, 29 May 1998
From: psic@uclink4.berkeley.edu (Paula Sicurello)
Subject: EMs in Turkey
Hello Listers,
A while back someone posted a note saying there was an EM facility
in Turkey. Would that person please e-mail me? I have a student who needs
to know what type of equipment you have and if she would be able to use it
while she was doing research in Turkey. She needs an ESEM because she is
working on archealogical samples that can not leave the country and can't
be sputter coated.
So PLEASE contact me as soon as you can so we can see if you can
help her. Thank you!
Paula :-)
Paula Sicurello
UC Berkeley
Electron Microscope Lab
psic@uclink4.berkeley.edu
Return to the List of Archived Articles
Date: 30 May 1998
From: Steve Chapman
Subject: re: EMs in Turkey
Hi Paula,
I am interested in your comment that "you need an ESEM because you can not
coat the specimen". True in many cases specimens will charge at "normal"
operating kilovoltages and beam currents. Have you tried the gentle
approach, "low charge techniques", with the type of specimen in question.
1. Lower kV, try 2 to 5kV for example on an instrument up to 10 years
old, on a newer instrument you could probably get down to 0.5 kV, it all
depends on the resolution that you require.
2. Lower the probe size, hence beam current, less electrons means a
greater possibility of those you are using getting away to earth.
3. Change the WD (and tilt), in different instruments different WD
(and tilt) give different signals to the ET detector there will always be a
position of minimum charge effect.
We are often in the situation that you describe and as ESEM are few and far
between we use low charge techniques on whatever instrument we happen to
have. All this is even better with LaB6 or a FEG system.
Steve Chapman
Senior Consultant E.M.
Protrain, 16 Hedgerley, Chinnor, Oxford OX9 4TN, England.
Tel & Fax 44 (0)1844 353161
Web Site - http://ourworld.compuserve.com/homepages/protrain
For Consultancy and Courses in Electron Microscopy World Wide
Return to the List of Archived Articles
Date: 30 Jun 1998
From: Jose Maria Manero
Subject: Observation of cell cultures in ESEM
High,
I'am studing osteoclasts cells culture "in vitro" on dentine slides in
an Environmental Scanning Electron (Electrosan 2020).
Is there anybody who has been working on this subject ?
I need some recomendations (kV, Working distance, Pv H2O), or litaracy
on this subject, because I didn't find anything.
Thank you very much.
Return to the List of Archived Articles
Date: 17 Aug 1998
From: William P. Sharp"
Subject: ESEMs and Biological Specimens
Hello to those in listserv land -
I'm a long time lurker (two or more years) first time poster. There have
been bunches of good stuff on the list that have saved me time, money and
effort, for which, thanks to all. Now, I actually have some questions that
I have not seen addressed as yet. A bit of background on me: I manage
Arizona State University's Life Science EM Lab and have for over twenty
years. We are a teaching and research lab with a STEM/EDS, a TEM, and an
old, non-functional SEM which is the crux of all my questions. We are
writing a grant proposal for a replacement for the SEM and have been very
interested in a Philips/FEI ESEM FEG for its apparent resolution,
flexibility, and all round usefulness. The questions we have are:
1) Can work be done on unfixed, hydrated biological specimens without cell
walls such as animal tissue and/or cultured cells?
2) Can this type of work be done at high resolution, either at high or low
KeV and how much beam damage does one expect?
3) Is manipulation of water vapor pressure / temperature (w/Peltier stage)
sufficiently precise to do this type of work routinely?
4) Do unprotected cells simply explode when introduced into the scope?
5) Does anyone out there have such a scope in a biologically based lab or
know someone who does??
6) We have searched the literature and found virtually NO bio based papers
in our meanderings. Are there papers we are missing? (we do know that FEG
ESEM is new and not many are about - how about the older Electroscan W
filament or LaB6 types? Are they amenable to high-ish resolution work on
bio stuff?
OK. TOO much bandwidth for a first post. Thanks in advance for any and all
info or leads.
---------------------------------------------------------------
William P. Sharp
Department of Botany
Arizona State University
Tempe, AZ 85287-1601
---------------------------------------------------------------
voice (602) 965-3210 | fax (602)965-6899 | email wsharp@asu.edu
Return to the List of Archived Articles
Date: 18 Aug 1998
From: scott.wight@nist.gov (Scott Wight)
Cc: cgilpin@fs1.sem.man.ac.uk, trice@electroscan.com
Subject: Re: ESEMs and Biological Specimens
William
Chris Gilpin is probably the most experienced
biological ESEM user and I know he sometimes posts to this list so I expect
you will hear from him. I hope he provides us all with a sample of
references to bio ESEM. I suggest you contact Trisha Rice at Electroscan
as she is probably the most experienced at ESEM FEG
and will be able to answer your FEG specific questions. Unfixed hydrated
biologicals can be examined with enough control to keep the specimen
hydrated. We have a LaB6 ESEM and do mainly materials and particles with
resolution comparable to conventional SEM, I suspect the same is true for
biologicals. Good luck,
Scott
Not an endorsement, no financial stake, just a satisfied customer.
>interested in a Philips/FEI ESEM FEG for its apparent resolution,
>flexibility, and all round usefulness. The questions we have are:
>1) Can work be done on unfixed, hydrated biological specimens without cell
>walls such as animal tissue and/or cultured cells?
>2) Can this type of work be done at high resolution, either at high or low
>KeV and how much beam damage does one expect?
>3) Is manipulation of water vapor pressure / temperature (w/Peltier stage)
>sufficiently precise to do this type of work routinely?
>4) Do unprotected cells simply explode when introduced into the scope?
>5) Does anyone out there have such a scope in a biologically based lab or
>know someone who does??
>6) We have searched the literature and found virtually NO bio based papers
>in our meanderings. Are there papers we are missing? (we do know that FEG
>ESEM is new and not many are about - how about the older Electroscan W
>filament or LaB6 types? Are they amenable to high-ish resolution work on
>bio stuff?
------------------------------------------------------------------
Scott Wight e-mail: SCOTT.WIGHT@NIST.GOV
NIST - Microanalysis Group W voice: 301-975-3949
Bld 222, Rm A113 | fax:301-216-1134/301-417-1321
Gaithersburg, MD 20899 \|/ disclaimer: Any opinion expressed is
my own and does not represent those of my employer.
Return to the List of Archived Articles
Date: 18 Aug 98
From: Debby Sherman
Subject: FWD: ESEMs and Biological Specimens
I too would appreciate information on this subject. Please post
responses to the listserve or, Bill, would you mind summarizing responses and then
posting the summary?
Debby Sherman, Manager Phone: 765-494-6666
Microscopy Center in Agriculture FAX: 765-494-5896
Dept. of Botany & Plant Pathology E-mail: sherman@btny.purdue.edu
Purdue University
1057 Whistler Building
West Lafayette, IN 47907-1057
--------------------------------------
Date: 8/17/98 6:38 PM
>From: William P. Sharp
Hello to those in listserv land -
I'm a long time lurker (two or more years) first time poster. There have
been bunches of good stuff on the list that have saved me time, money and
effort, for which, thanks to all. Now, I actually have some questions
that
I have not seen addressed as yet. A bit of background on me: I manage
Arizona State University's Life Science EM Lab and have for over twenty
years. We are a teaching and research lab with a STEM/EDS, a TEM, and an
old, non-functional SEM which is the crux of all my questions. We are
writing a grant proposal for a replacement for the SEM and have been very
interested in a Philips/FEI ESEM FEG for its apparent resolution,
flexibility, and all round usefulness. The questions we have are:
1) Can work be done on unfixed, hydrated biological specimens without
cell
walls such as animal tissue and/or cultured cells?
2) Can this type of work be done at high resolution, either at high or
low
KeV and how much beam damage does one expect?
3) Is manipulation of water vapor pressure / temperature (w/Peltier
stage)
sufficiently precise to do this type of work routinely?
4) Do unprotected cells simply explode when introduced into the scope?
5) Does anyone out there have such a scope in a biologically based lab or
know someone who does??
6) We have searched the literature and found virtually NO bio based
papers
in our meanderings. Are there papers we are missing? (we do know that FEG
ESEM is new and not many are about - how about the older Electroscan W
filament or LaB6 types? Are they amenable to high-ish resolution work on
bio stuff?
OK. TOO much bandwidth for a first post. Thanks in advance for any and
all
info or leads.
---------------------------------------------------------------
William P. Sharp
Department of Botany
Arizona State University
Tempe, AZ 85287-1601
---------------------------------------------------------------
voice (602) 965-3210 | fax (602)965-6899 | email wsharp@asu.edu
Return to the List of Archived Articles
Date: 19 Aug 1998
From: "Chris Gilpin"
Subject: RE2: ESEMs and Biological Specimens
William and the list,
My thanks firstly to Scott for the recommend.
I have been using a tungsten ESEM for biological work for the last 6 years.
Although I have published little in print I have presented at numerous
meetings. So only abstracts in the literature I'm afraid. OK a couple of
papers on EDX in ESEM and some on pharmaceutical applications but not
strictly biological.
Now to your questions!
1) Yes you can work on unfixed hydrated samples.
2) depends on what you call high resolution
3) manipulation of hydration is easy with a little practice.
4) no cells do not explode.
5) Yes, I have a tungsten E3 and have used a.n.other FEG ESEM for biology.
6) See my opening my remarks
Those are the simple answers!
To adequately cover the detailed answers would take up much space. Here are
my main thoughts for other list readers. I can give a fuller account off
list if it will help.
Cells often look very different when examined by ESEM compared to Hi VAC. I
have always taken this to represent a "truer" view of biological surfaces -
very smooth with little fine topography. I assume that extracellular matrix
is well preserved with ESEM giving this appearance. Hence the comment on
resolution. The microscope is capable of matching Hi Vac for resolution but
many biological structures do not have that much detail to show.
Aesthetically disappointing but with correct interpretation valuable
information on structure. Low KV is difficult with a tungsten ESEM but not
impossible. I routinely image at 5KV. Modification of the detector (as per
Brendon Griffin)allows imaging at a few hundred volts. Beam scattering in
the chamber gas is the problem and simple physics shows that the more
electrons you start with (FEG > LaB6 > W)) the more will reach the sample.
You are right to highlight hydration as being important. Very fine control
is easy with the older instruments but I worry about the vacuum increment
steps in the windows driven new instruments. 0.1 Torr or 10 Pa is not really
fine enough but still possible.
I have come to the conclusion that many cells are best viewed hydrated but
after a short fixation in glutaraldehyde and rinse in water. This has a
number of benefits. Fresh samples which arrive at 5 o'clock on a Friday can
be examined on Monday morning! Beam damage is greatly reduced. Finally cells
cannot be examined from culture medium or buffers because the salts
precipitate out following excess liquid removal obscuring anything of
interest. Unfixed samples can be examined but my experience has shown that
the structure is pretty similar in both cases. It is dehydration that causes
the problems not fixation. Remember that cryo stages are also available for
ESEM - just use different chamber gas (see papers from the Cavendish group
in Cambridge). Cells tolerate the vacuum (at least 4.6 Torr to be hydrated
above freezing) well. Electroscan/FEI/Philips have video on moving insects
in their promotional material.
One final point to make. If you have an ESEM you also have a very capable Hi
Vac and controlled pressure instrument as well. Don't fall into the trap of
should I get ESEM OR conventional - you can have both in one instrument!
Another final point! The images obtained in ESEM mode should be taken as
another piece of information in a bigger picture and should be seen as
complementary to other SEM techniques.
My own opinions as a satisfied customer (how about a free upgrade Ralph?)
Chris Gilpin
Experimental Officer
Biological Sciences EM Unit
University of Manchester
Oxford Road
Manchester
M13 9PT
Phone +44 (0)161 275 5170
Fax +44 (0)161 275 5171
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Date: 24 Sep 1998
From: "Ziel, R. (Rainer)"
Subject: ESEM: Use of Helium Gas -- Summary
Thank You for all the answers given to my question about using Helium
gas in the ESEM:
I asked:
Stowe and Robinson report about reducing beam scattering in conventional
Low Vacuum SEM's (Scanning, Vol. 20, 57-60). Are there any experiences
using Helium in an ESEM from Electroscan or Philips with a special
ESEM-detector? Is the ionization efficiency high enough to get a good
performance for amplifying the electrons coming from the sample? How is
the image quality compared to e.g. water vapor?
Kind regards
Rainer Ziel
------------------------------------------------------------------------
--------------------------
Roger Moretz wrote:
I can't give you the exact answers you are looking for, but hopefully
the following can point you in the right direction. At the '99 MSA
meeting in Atlanta, there was a session on ESEM. Several papers were
given by the group from the Cavendish Laboratory, especially one on SEM
at freezer temperatures by A.L. Fletcher, ... & A.M. McDonald. In an
attempt to maintain the proper humidity without icing or thawing, this
group used other gases, and determined that N2 was minimally acceptable
in terms of obtaining desired imaging SEs. Discussion following the
paper included comments on the scattering and SE generation that could
be expected from lower atomic number gases, including He. I would
suggest your contacting this group. Additionally, I would recommend
that you do a literature search for the work of K. Rudiger-Peters and
the various publications he has on the physical characteristics and SE
generation in the ESEM. I think most of those papers were in the
journal Scanning. The principal author on the ESEM is of course
Danilatos, and his publications span from 1982 to 1990. Since I do not
have ready access to those publications (everything is in boxes, no
longer arranged as per my reference manager database) I can't give you
figures or exact references even, but I believe that he did publish on
different gases. Hope this helps.
Roger Moretz
Toxicology
Boehringer Ingelheim Pharmaceuticals, Inc.
------------------------------------------------------------------------
------------------------------------
Bradley L. Thiel wrote:
The question that you posted to the microscopy list server was passed on
to me. We have investigated the imaging and amplification properties of
several gases in the ESEM. Unfortunately, we have not been very
efficient
at publishing the results....
Helium actually works very well in the Philips-ElectroScan instruments.
However, it is not a very efficient signal amplifying gas, so the
emperical results can be a bit deceiving. First, because of the small
elastic scattering, the probe-skirt formation is much reduced relative
to
water vapour. Second, the gas is even less efficient at amplifying the
spurious signal from primary beam and backscattered electron
ionisations.
This means that although the signal collected by the ESD/GSED is not
amplified much, it is a very pure secondary signal. The reduced skirt
also gives stronger useful contrast.
Unlike other gases, He does not exhibit a peak in its amplification
efficiency within the pressure range accessible in the ESEM. It is
difficult maintaining pressures above about 8 Torr, because of
backstreaming up the column. RP3 has a difficult time pumping the large
volume of He.
Consequently, you should use a moderate pressure of gas, avoid detector
biases that give arcing, and use the electronic signal amplifier and/or
image integration to get a good image.
You may wish to see
A.L. Fletcher, B.L. Thiel, and A.M. Donald, Journal of Physics D:
Applied
Physics, Vol. 30, 2249-2257 (1997).
for some discussion of gases.
I hope this is of some help to you. Please feel free to contact me if
you
have other questions.
Best Wishes,
Brad Thiel
Polymers & Colloids Group
Cavendish Laboratory
Department of Physics
University of Cambridge
------------------------------------------------------------------------
--------------------
Warren Straszheim wrote:
We routinely use He in our Hitachi 2460N, but we normally run at 40 Pa
and
use a backscattered electron detector. The resolution is _much_ better
than
air, and probably better than water vapor. I don't know how it would
behave
with the specialized sec. e detectors.
Also recall seeing at least one slide on the effect of gas type and
pressure
on scattering during ESEM sessions at the Atlanta MSA meeting. Sorry, I
cannot remember who showed it.
Warren
------------------------------------------------------------------------
--------
Thank You
Rainer Ziel
-------------------------------------------------------------
Dipl.-Phys. Rainer Ziel
Akzo Nobel Central Research
ACR-O/RMG-EM
63784 Obernburg
Tel: (06022) 81-2645
Fax: (06022) 81-2896
E-mail: Rainer.Ziel@AkzoNobel.com
Return to the List of Archived Articles
Date: 27 Sep 1998
From: William Tivol
Subject: Re: ESEM: Use of Helium Gas -- Summary
Dear Sally,
>
> 3. Permeability -the EDS on our VP system has a Be window, and we
> havent had obvious problems resulting from helium. However somebody
> with an ultra-thin window EDS once mentioned that after using helium
> for leak testing, they thought some gas had found its way into the
> EDS detector. Not a good prospect, especially given the thermal
> properties. Does anyone have any more information or experience
> relating to this?
>
When I was a grad student studying the scattering of protons on
He, we had a target which was an evacuated, completely sealed thin glass
sphere. The target was filled by immersing the sphere in a container
filled with He. The He would diffuse through the sphere, which we would
then use until sufficient He had diffused out. Since the glass was thick
enough to be mechanically self-supporting, one can conclude that He will
diffuse quite readily through many materials usually considered imper-
meable. I'm not surprised that He can get through an ultra-thin window,
but I would be surprised if it didn't also get through a Be window. I
would also not expect obvious problems from the relatively small amount
of He which got through the small area of an EDS window.
Yours,
Bill Tivol
Return to the List of Archived Articles
Date: 26 Sep 1998
From: "Sally Stowe"
Subject: Re2: ESEM: Use of Helium Gas -- Summary
A few more caveats and questions - helium can certainly produce a
dramatic difference in image quality and the amount of X-ray scatter,
especially at lower kVs. We are using it a lot in CL imaging as
well. However there are a couple of complications arising from its
increased thermal conductivity relative to nitrogen or air. -
temperature at the specimen surface MAY be a little higher than in
other gases, depending on the detector positions I suppose.
-2. Pressure readout from a gauge depending on a thermal effect, as
in the Piranis used in most chamber pressure control systems, will
be more in helium than nitrogen at the same pressure. There are
graphs around. The diifference is
not very much in the 0.01-0.1 torr range, but diverges very rapidly -
from memory an indicated pressure of 3.5-4 torr corresponds to a
true pressure of only about 1.3 torr. Which may affect the
pressure range a gaseous amplification system thinks it is working
at? (Ionisation potential of helium is about 25eV, cf 15eV for
nitrogen...I dont know if that is enough to have a big effect on
detector efficiency?)
We only use BSE and CL, so I've no data on
this, but for what its worth in the pressure range we use, we dont
get the swamping background CL signal in helium that comes in at
higher pressures in air.
havent had obvious problems resulting from helium. However somebody
with an ultra-thin window EDS once mentioned that after using helium
for leak testing, they thought some gas had found its way into the
EDS detector. Not a good prospect, especially given the thermal
properties. Does anyone have any more information or experience
relating to this?
>
Rainer Ziel wrote -
> Thank You for all the answers given to my question about using Helium
> gas in the ESEM:
> I asked:
>
> Stowe and Robinson report about reducing beam scattering in conventional
> Low Vacuum SEM's (Scanning, Vol. 20, 57-60). Are there any experiences
> using Helium in an ESEM from Electroscan or Philips with a special
> ESEM-detector? Is the ionization efficiency high enough to get a good
> performance for amplifying the electrons coming from the sample? How is
> the image quality compared to e.g. water vapor?
>
> Kind regards
>
> Rainer Ziel
Return to the List of Archived Articles
Date: 21 Oct 1998
From: "NICOLA BOCK"
Subject: SEM Heating stages
Dear Microscopists
We are looking to purchase a heating stage for our Philips FEG ESEM.
We have information about the Philips stage which can reach 1000C but
some workers will require still higher temperatures, and their 1500C
stage is not on the market yet. Does anyone have experience of using
heating stages and at what temperatures? How do different
manufacturers compare and how easy are other stages to adapt to the
ESEM. In particular will we still be able to use the Gaseous SE
detector or are they designed for use with cooled conventional SE
detectors?
Any info will be much appreciated.
Cheers
Nikki
Nikki Bock
EM Technician
Dept. Materials Engineering
University of Nottingham
Nottingham NG7 2RD
(0115) 9513759/9513871
Email: emznjb@hermes.nottingham.ac.uk
Return to the List of Archived Articles
Date: 21 Oct 1998
From: Mary Mager
Subject: Re: SEM Heating stages
>
Dear Nicola,
I would suggest you try a company, such as Deben UK Ltd.
(http://www.deben.co.uk), that make special stages for any microscope. They
should be able to answer your questions.
You wrote:
>Dear Microscopists
>
>We are looking to purchase a heating stage for our Philips FEG ESEM.
>We have information about the Philips stage which can reach 1000C but
>some workers will require still higher temperatures, and their 1500C
>stage is not on the market yet. Does anyone have experience of using
>heating stages and at what temperatures? How do different
>manufacturers compare and how easy are other stages to adapt to the
>ESEM. In particular will we still be able to use the Gaseous SE
>detector or are they designed for use with cooled conventional SE
>detectors?
>Any info will be much appreciated.
>
>Cheers
>Nikki
>
Regards,
Mary
Mary Mager
Electron Microscopist
Metals and Materials Engineering
University of British Columbia
6350 Stores Road
Vancouver, B.C. V6T 1Z4
CANADA
tel: 604-822-5648
fax: 604-822-3619
e-mail: mager@interchg.ubc.ca
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Date: 21 Oct 1998
From: Ron Doole
Subject: Re2: SEM Heating stages
Hi Nikky,
I cannot answer your question directly as I have not used SEM hot
stages but I do use TEM hot stages in a variety of different gasses and
pressures.
My hot stage uses a W heating element and will get to 1000C in
vacuum. However, it will only get to 700C in 20mbar H or He before it
burns out as it needs so much more power to overcome the heat loss in the
gas. It will only hold 350(ish)C in oxygen before the W oxides finally
burn the wire out, 300C is OK, for hours 400C for tens of minutes.
Other gasses have similar problems. These problems could be improved or
eliminated with better stage design or alternative materials.
Check specification of the hot stages under the gas type and
pressures that you are interested in working at.
Good luck,
Ron.
===========================================================================
Mr. Ron Doole e-mail ron.doole@materials.ox.ac.uk
Department of Materials, phone +44 (0) 1865 273701
University of Oxford, fax +44 (0) 1865 283333
Parks Road.
Oxford. OX1 3PH. UK.
============================================================================
Return to the List of Archived Articles
Date: 22 Oct 1998
From: Charles Butterick"
Subject: Re[3]: SEM Heating stages
THE 1500 degree heating stage is in productionn. Jo Long and
Trisha Rice of Philips indicated that there are 4 or 5 in use
already. FURTHER, another 1500 degree stage was being installed
today in their demo lab in Mass. Give your Philips rep another
call.
Return to the List of Archived Articles
Date: 15 Dec 98
From: Debby Sherman
Subject: FEG,ESEM or LV-SEM?
Biological SEM users:
I got very little response to the message I posted a week ago (see
below). It appears that at the present time there is not a great deal of
biological data from FEG-SEMs. To help us determine the best instrument to
consider for biological data accumulation, I would also like to explore
the pros and cons of the FEI/Philips'ESEM with the low vacuum instruments
available from other manufacturers. I have the brochures, etc from a number
of companies so am not looking for more of the same. I also have looked
into the basic design differences and detector differences.
What I would appreciate is comments from users based on their
experiences.
Why did you choose the instrument you did?
What type of information are you getting from your instrument of choice
that you could not get from a conventional SEM?
Do you also have a cryo unit and x-ray detector and, if so, what are the
limitations for their use in low vacuum modes?
How many hours per week is your instrument used and what percentage is in
the low vacuum mode?
Do you have other conventional SEMs or is this your only instrument?
Any other information would be appreciated. If the response is adequate,
and off-line, I will try to summerize.
Thanks,
Debby Sherman, Manager Phone: 765-494-6666
Microscopy Center in Agriculture FAX: 765-494-5896
Dept. of Botany & Plant Pathology E-mail: sherman@btny.purdue.edu
Purdue University
1057 Whistler Building
West Lafayette, IN 47907-1057
-----------------------------------------------
Earlier post (12/7/98):
I would like to hear from microscopists who have used FEG-SEM's and
particularily the semi-in-lens models for biological applications. I
would
also appreciate info on recent papers where this instrumentation was
critical to the biological research reported. Also any recommendations
as to
ideal samples for testing these microscopes for biological application?
Debby
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Date: 17 Dec 1998
From: "Chris Gilpin"
Subject: RE: FEG, ESEM or LV-SEM? +OM and SEM dont agree
1) Why must you make a choice between these different instruments?
The FEGESEM allows imaging in either ESEM mode or hivac - user choice.
ESEM has come a long way since its beginnings and is worthy of full
investigation.
There is no need to have surface water present when imaging in ESEM mode.
Control of the specimen chamber environment allows an experienced user to
remove surface water without dehydrating the sample.
2)The other factor which has not been mentioned when trying to relate OM to
SEM is the effect of vacuum on the sample. There has been some nice work on
textile fibres by David Taylor in Leeds using SEM and ESEM on the same
fibres showing what must be high vacuum effect.
Chris
Chris Gilpin
Experimental Officer
Biological Sciences EM Unit
G452 Stopford Building
Oxford Road
Manchester
M13 9PT
phone +44 0161 275 5170
Fax +44 0161 275 5171 Chris Gilpin
http://www.empgu.man.ac.uk
Debby;
The decision on which microscope to purchase depends on what type of work
and samples your lab will be handling. If you will be doing a lot of high
resolution work on fixed samples a FEG is great. We have a field emission
Hitachi SEM, an S4000. For low voltage work on biological samples it makes
fantastic images, but they need to be fixed, dried and coated. They have
exquisite detail, but if your sample cannot withstand the preparation or
your client is unwilling to pay for all the preparation, the results will be
disappointing. I do not have much experience with ESEMs, but from what I
have seen, I am not very impressed. They are the ultimate in ease for
looking at unfixed, wet samples, but the images from the ones I have seen
have looked pretty blah (a technical term). I think this is not just a
function of the image formation system in the scope, but of what you are
actually seeing, water. With all of the water present in a liquid form, it
flows and covers up the surface detail. I think that the combination of a
FEG with cryostage would be excellent compromise. It would allow looking at
unfixed samples, with everything in place without the time and expense of
the preparation, with all of the advantages of the FEG. It would also keep
the water were it was at the time of freezing. With sublimation, excess
water can be removed, thus exposing surface structures which may have been
covered. If you plan on looking at pollen and spore distributions, a
cryostage can make all the difference.
Bill
William McManus
Supervisor
Electron Microscopy Facility
Department of Biology
Utah State University
Logan UT 84322-5305
billEMac@cc.usu.edu
435-797-1920
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Date: 14 Mar 1999
From: Jim J Darley
Subject: RE: Removing gold from fossils
Getting gold off museum fossil pieces is nay impossible. Al
would be easier but basically its the same problem. C
coating is good enough for low powers, but again, Curators
do not like that dark coating,
To view these "hard, dry and non-conducting" specimens
uncoated, the best solution is a poor vacuum SEM; a fully
fledged Environmental SEM would also do well, but its a
more expensive instrument for that job. Poor vacuum SEM's
(I believe at least a couple of the major manufacturers
make instruments with that facility) use only mechanical
pump vacuum in the specimen chamber and because of a vacuum
limiting aperture retain high vacuum in the gun chamber.
Secondary mode is impossible, but a Robinson detector gives
excellent images for this type of work. Magnifications
under these conditions are limited to about 2000x, but
details in fossils do not warrant higher magnifications;
its the SEM's superior depths of field that wins out over
light microscopy.
Kim - all you require now is one of those scopes!
Years ago I modified an Etec Autoscan to function
reversibly as a poor vacuum instruments. It worked well but
it was a fair bit of trouble to accomplish the required
modifications.
Our online contain a link to an archive collated by Scott
Wight. This contains listserver contributions concerned
with Environmental and Poor Vacuum SEM.
Cheers
Jim Darley
ProSciTech Microscopy
PLUS
PO Box 111, Thuringowa QLD 4817 Australia
Phone +61 7 4774 0370 Fax: +61 7 4789 2313
Great microscopy catalogue, 500 Links, MSDS, User Notes
********************** www.proscitech.com.au *****
On Saturday, March 13, 1999 6:55 AM, Kim DeRuyter
[SMTP:fnksd1@uaf.edu] wrote:
>
> Hi,
> A student in the lab is looking at museum samples of
> dinosaur bones and
> teeth on the SEM. He could get access to more samples if
> he could restore
> them to their original condition ( ie, remove the gold).
> Is there a good
> nondestructive way to do this?
>
> Kim DeRuyter
> Histology and Electron Microscopy Labs
> University of Alaska Fairbanks
>
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Date: 20 Mar 1999
From: "Sally Stowe"
Subject: Removing gold from fossils/SE detection
I agree with Jim that the best way to deal with gold on museum specimens, artwork, taxonomic
type specimens, fossils etc is to leave it off in the first place where possible. The material
can sometimes be viewed in a normal SEM by keeping kV and probe current low, or generally more
conveniently by using one of several types of variable pressure SEM. Until recently the cheaper
versions, working up to about 2 torr, were restricted to non-SE detection modes (BSE, CL, absorbed
current etc) but several SE detector systems working in this range have become commercially available.
We have just installed a new Robinson detector which allows convenient BSE and/or SE detection
to low kV, in high vacuum or variable pressure conditions, on a small Hitachi NSEM. (1992) and
find the combination mode in particular gives very good results for topographic imaging.
beats explaining a caustic cyanide stew to your friendly curator, I should think.
cheers
Sally
Dr Sally Stowe
Facility Coordinator
Australian National University EM Unit
Research School of Biological Sciences
Box 475,
ACT 2601, Canberra, Australia
FAX 06 (0)2 6279 8525
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Date: 29 Mar 1999
From: "manoj misra"
Subject: ESEM Tensile Stage
Hello,
I am interested in finding out if there is any facility that has an ESEM
Tensile Stage with Peltier capabilities for structure/function studies using
ESEM.
Manoj
*****************************
Manoj Misra
Advanced Imaging and Measurement
Unilever Research, Edgewater, NJ 07020
(201) 840-2702 (V)
(201) 840-8299 (F)
E Mail: Manoj.Misra@unilever.com
****************************
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Date: 31 Mar 1999
From: Joergen Bilde-Soerensen 5802
Subject: Re: SEM and wood
Birna wrote:
> My name is Birna Gudbjoernsdottir working at Icelandic Fisheries
> Laboratories as a food scientist. This field is quite new to me and I am
> looking for information how I can prepare wood samples, both wet nad dry,
> for SEM. Any information would be greatly appreciated.
Dear Birna,
If you wish to keep the wood wet, you will have to use an
environmental SEM (ESEM), in which you can examine the sample with a
pressure above 5 torr (the equilibrium pressure of water vapour just
above 0 degree C) in the specimen chamber. If you can accept that the
wood slowly dries, you may use a low-vacuum SEM (LVSEM) where you can
work with a pressure of up to 1-2 torr. Both ESEM and LVSEM allows
the examination of electrical insulators.
In the conventional high vacuum SEM you cannot have wet wood. Dry
wood may be examined, but then the surface must be made conductive
e.g. by sputtering gold onto the sample.
Best regards,
Joergen.
J. B. Bilde-Soerensen
Senior Research Scientist, Ph. D.
Materials Research Department
Risoe National Laboratory
DK-4000 Roskilde
Denmark
e-mail: j.bilde@risoe.dk
phone: +45 46 77 58 02 (direct)
phone: +45 46 77 46 77 (switchboard)
fax: +45 46 77 57 58
website: http://www.risoe.dk/afm/Personal/jqbi/jqbi.htm
>
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Date: 31 Mar 1999
From: "Emond W F de Roever"
Subject: Re: ESEM Tensile Stage
The Swedish Pulp and Paper Research Institute has a tensile stage on
the ESEM 2020 (+ Peltier) and has used it extensively. Contact
joanna.hornatowska@stfi.se
Not nearby; with best regards, Emond de Roever
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