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

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*

Ellery and Marc,
      We have just had our SX-100 refitted with such an electron  
source but have not experimented with it yet.
      There are advantages to the system, principally in a longer  
lasting and brighter source.  However, even with an infinitely narrow  
beam, the analytical volume cannot be reduced below a fixed amount,  
typically 1-2 microns across if the operating voltage is 10-15 kV,  
also depending of course on the ave. Z of the specimen.  The volume  
is reduced considerably if operating at a few kV, but then one cannot  
excite characteristic X-ray lines that can be detected for many  
elements.
eric


On Sep 27, 2007, at 12:42 PM, Ellery Frahm wrote:

> JEOL Probe Users Listserver
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> Moderator: Ellery Frahm, [log in to unmask],
> Electron Microprobe Lab, University of Minnesota
>
> Post a message: send your message to [log in to unmask]
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>
>
> *
>
> Probe folks,
>
> Today I received the following message from one of the professors  
> in our department:
>
>> Ellery,
>>
>> I was just at a meeting where a colleague was telling me about his  
>> SX-100 microprobe and the amazing improved spatial resolution it  
>> gets for both imaging and quantiative analyses owing to the LaB6  
>> source. It's my understanding that JEOL sells the 8200 with an  
>> option of a LaB6 or tungsten filament source.  Do you know if JEOL  
>> will retrofit 8900s with Lab6 and if so, how much it costs?  The  
>> fellow with the SX100 says that Cameca charges something like $10k  
>> extra for a LaB6 source on the SX-100...
>>
>> Marc
>
> Is such a refit possible or feasible?  I know it is easy to go from  
> LaB6 to W filament, but it seems harder to go the other way.  I  
> believe that we'd need an ion pump at the top of the column for  
> LaB6, but would a turbo pump need necessary too or are diffusion  
> pumps okay?  Are the electronics, heating system, etc. the same or  
> not?
>
> I am also curious if anyone is currently running or has recently  
> run a LaB6-outfitted machine.  Are the concerns about beam  
> stability valid, or is the issue overblown?  What is the typically  
> stability in your experience?  What are current opinions about  
> LaB6?  Having never used a LaB6-equipped microprobe, I don't have  
> any first-hand experience or observations on which to draw.
>
> Any facts, observations, opinions, wild speculations, or hearsay  
> are welcome.
>
> Best,
> Ellery
>
> --------------------
> Ellery E. Frahm
> Research Fellow & Manager
> Electron Microprobe Laboratory
> University of Minnesota - Twin Cities
> Department of Geology & Geophysics
> Lab Website: http://probelab.geo.umn.edu
> Personal Website: http://umn.edu/~frah0010
>
>