Dear Debashis,

If you want to answer that question, you need to perform GDOS to your
plasma. In your plasma you can find many light-emitting species, like
neutral Ar, ionized Ar, H2O, N2, your sputtered elements... The change in
color will be due to a change on the emission intensity of the species of
the plasma which is related to amount of each element in the plasma.
Unfortunately just by the color you can't know for sure what's happening.

Enrique San Andrés.

-----Mensaje original-----
De: DEBASHIS MAJI [mailto:ece.debashis@gmail.com]
Enviado el: martes, 07 de septiembre de 2010 14:30
Para: General MEMS discussion
Asunto: [mems-talk] Argon plasma color

Dear All,

I would like to ask why does the color of the argon plasma during sputtering
changes form light purple to bright blue as the deposition power is
increased or the working pressure is increased to about 0.1 m bar? Is the
shift in color towards deep blue, due to formation of increased number of
energy states...? if so  how is it happening with increased power and/or
with increased working pressure..?

Thanks in advance....

Debashis Maji,