[NewCandle] los artifactos

[Nick Reiter]

Quick note to John and all,

When I made my witness piece of Al foil with Ag
deposited on it, I was guesstimating the thickness I
would need to give an Ag signal only slightly higher
than the one I was seeing on the corroded pieces
(according to the semiquant on the EDS).  One of the
little empirical bits of lore I tapped on in making
that guesstimate was past experience with doing some
forensic work on solar cell metal contacts, looking at
a contact structure that contained Mo, Cr, and a thick
layer of Al.  About 200A (from documentation) seemed
to give about the same relative signal strength for Cr
and Mo as I was looking for (a signal the semi-quant
would call about 2 to 3 atomic %.)

When I deposited the silver, the crystal thickness
monitor was acting up.  So I may have had quite a bit
more than 200A, but I also arranged my foil in the
bell jar on a mask so I would have a graded region I
could snip out and sample at different spots.  Had to
make do with what I could slip into the stream of work
for the "day job".  I definitely had enough on the
foil that at one end, I got about a 5 at% value, which
showed a noticeable 3.151keV peak.  As I moved away
from that, the 3.151 sank away first, but the main La
peak still diminished until reaching a minimus, which
then seems to be the un-altered double count Al.

n


> interaction volume of <0.2 µm at 5 kV, compared to
> an interaction volume 
> depth of 1.5 to 2.0 µm at 15 kV". You will note that
> your silver layer 
> was only 0.02 µm thick and you are running at 30kV -
> which probably 
> gives you an interaction depth of 3 to 4 µm, and a
> pear-shaped (or 
> approximately spherical) volume centered at that
> depth. So you are 
> sampling many hundreds, if not thousands, of times
> more volume of 
> aluminum than silver. 


The Holy Grail 'neath ancient Roslin waits.
The blade and chalice guarding o'er Her gates. 
Adorned in the masters' loving art, She lies;
She rests at last beneath the starry skies.