FEG microscope problems

[hainfeld at bnl.gov]

this may not be the right ans, but:
field emitters have electrons coming off of low work function crystal 
surfaces.  the tip is usually 111 oriented W.  But emission comes from the 
other surrounding planes, and if not blocked will focus to multiple beams.
J. Hainfeld

At 02:52 PM 5/8/2003 +0800, Terje Dokland wrote:

>We recently had a new JEOL 2010FEG microscope installed. However, after 
>installation, we find that there is not one, but four to six beam spots!
>
>The technician says it is due to magnetic interference. He also claims 
>that it has no effect on resolution, and that may be true with respect to 
>gold or graphite, but I'm sure it can't be very good for coherence and 
>phase contrast, and hence the whole purpose for having an FEG is lost!
>
>Has anybody else had such experience with an FEG microscope? Was it due to 
>magnetic interference, and was there a way to fix it? We will try a 
>magnetic field canceler in a few weeks time. Is this likely to work? 
>Suggestions are welcome, as I am not too happy to pay for the microscope 
>until this problem has been solved!
>
>terje
>
>--
>------------------------------------
>Dr. Terje Dokland
>Senior Scientist
>Institute of Molecular and Cell Biology  <--- NOTE NEW ADDRESS !
>1 Research Link, A*STAR Building
>Singapore 117604
>Phone: 65-6872 7405  Fax: 65-6872 7007
>E-mail: dokland at imcb.nus.edu.sg
>
>"Convictions are greater enemies of truth than lies"
>                                 F. Nietzsche
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Dr. James F. Hainfeld  *  hainfeld at bnl.gov
Brookhaven National Laboratory  *  Biology Dept.  *  Bldg. 463  *  Upton, 
NY  11973   USA
Tel.  631-344-3372  *  Fax. 631-344-3407
website: http://bnlstb.bio.bnl.gov/biodocs/stem/stem.html

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