Why freeze autorads?

[William P Prichett]

Sam,
    The answer to your question comes down to photochemistry/physics.  
The silver grains require energy from more than one electron to take it 
to a stable energy level that would thus be considered exposed and will 
the develop in the photographic chemicals.  Thus it need multiple 
collisions to absorb enough energy and if it does not, it will revert to 
ground state.  In the cold the partially energized silver grains are kept 
a little more stable while awaiting more collisions to raise it to a 
truely stable energy level.  And this produces a better sensitivity.  
This is a laymans explanation, as I am not a chemist, but a a biochemist 
 (Big difference).

Bill
Samuel C. Blackman wrote:
> 
> My labmates and I, obviously with too much time on our hands, were
> wondering why we put our 32P-labelled autorads in the freezer at -80C.
> Our advisor hypothesized that the low temp. promotes a more "focused"
> autorad, but without a good explanation for that.  The decay equation
> has no mention of temperature, so we're stumped.  Any ideas?
> 
> -- Sam
> 
> --
> Samuel C. Blackman        ! InterNet : blackman at tigger.uic.edu
> MD/PhD Student (4/8)      ! Disclaimer: I speak for me, not UIC!
> Univ. of Ill. at Chicago  ! Quote : "Quandro potro io finir di stupire?"
> Dept. of Pharmacology     ! Phone : 312/996-4983 (lab)  Fax: 312/996-1225

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