PROBEUSERS Archives

August 2006

PROBEUSERS@LISTS.UMN.EDU

Options: Use Monospaced Font
Show Text Part by Default
Condense Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Sender:
JEOL-Focused Probe Users List <[log in to unmask]>
X-To:
John Fournelle <[log in to unmask]>
Date:
Tue, 29 Aug 2006 09:51:12 -0400
Reply-To:
JEOL-Focused Probe Users List <[log in to unmask]>
Subject:
MIME-Version:
1.0
Content-Transfer-Encoding:
7bit
Content-Type:
text/plain; charset=iso-8859-1
From:
James McGee <[log in to unmask]>
Parts/Attachments:
text/plain (114 lines)
JEOL Probe Users Listserver

Moderator: Ellery Frahm, [log in to unmask],
Electron Microprobe Lab, University of Minnesota

Post a message: send your message to [log in to unmask]

Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]

On-line help and FAQ: http://probelab.geo.umn.edu/listserver.html



*

John,

I don't know if the server will accept my post from my work address, so
please forward if necessary.

Your question is about kV for EBSD, which is electron channeling, not X-ray
analysis.  The resolution of EBSD signal is ~ linear with kV.   Lower kV is
better for resolution of the EBSD signal because you have a smaller
interaction volume of beam with sample.    But higher kV will give you
better signal (like BSE).  Other contributing factors such as amount of
deformation, grain size, sample prep (very important in EBSD), working
distance, come into play.

My EBSD-expert colleague says that 20kV is the defacto standard (sort of the
way 15kV has become the geoscience X-ray spectrometry standard), optimizing
resolution and signal.


Jim
*******************************
James J. McGee
Materials Engineer / Electron Microscopist
Mail Bin 149
Lockheed Martin- KAPL, Inc
PO Box 1072
Schenectady NY 12301-1072

email: [log in to unmask]
tel: 518-395-4612


 ----- Original Message ----- 
> From: "John Fournelle" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, August 22, 2006 2:53 PM
> Subject: [PROBE-USERS] EBSD question: what kev is good?
>
>
> > JEOL Probe Users Listserver
> >
> > Moderator: Ellery Frahm, [log in to unmask],
> > Electron Microprobe Lab, University of Minnesota
> >
> > Post a message: send your message to [log in to unmask]
> >
> > Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]
> >
> > On-line help and FAQ: http://probelab.geo.umn.edu/listserver.html
> >
> >
> >
> > *
> >
> > We have acquired a nice new SEM (W filament, variable pressure Hitachi
> > S3400) whose function principally is quality CL imaging (Gatan
PanaCL/F),
> > and EBSD (HKL) work.
> >
> > We have a question for labs out there with more EBSD experience under
> > their belts than we do: have you determined an optimal keV setting, for
> > any/all of your work? (we are doing geological work)
> >
> > It seems to me that you don't want to go to higher keV than necessary as
> > the scattering will increase (though the effective backscattered, oops
> > forescattered electron signals that are relevant may only be those from
> > the first events near the surface, suggested by Prior [1999]) and the
> > spatial resolution will decrease (though I am not convinced about
this) -- 
> > or does going to high keV improve the signal generated on the phosphor
> > screen and thus improve the Kukchi line discrimination?  Clearly having
> > significant counts (=high enough current) is probably the most important
> > factor, but given that is not a problem, would say 30 keV yield better
> > results vs 15 keV?
> >
> > thanks.
> >
> > John
> > -- 
> > ========================================================
> > John Fournelle, Ph.D.        office: (608) 262-7964   cell: (608)
438-7480
> > Cameron Electron Microprobe Lab   lab: (608) 265-4798
> > Dept of Geology & Geophysics      fax: (608) 262-0693
> > University of Wisconsin          home: (608) 274-2245
> > 1215 West Dayton St.            email: [log in to unmask]
> > Madison, WI 53706 amateur radio: WA3BTA
> >      Personal    http://www.geology.wisc.edu/~johnf/
> >      Probe lab   http://www.geology.wisc.edu/~johnf/sx51.html
> > Probe Sign Up Calender:
> > http://www.microscopy.wisc.edu/cgi-bin/calendar/microprobe/calendar.cgi
> >
> > "The first rule of all intelligent tinkering is to save every cog and
> > wheel." --  Aldo Leopold
> >
> > "For a successful technology, reality must take precedence over public
> > relations, for Nature cannot be fooled."    --   Richard P. Feynman
>
>

ATOM RSS1 RSS2