Some further explanations are required to describe, how the metal oxide nanoparticles are formed (i.e. where is the oxygen coming from?).
Hello,
the following effects has to taken into account:
1) when deposition is done in high vacuum the main oxygen source is the residual gas (the most abundant component in a non-baked system is water vapour). To get rid of it deposition must done like in MBE: baked system and a lot of shrouds (cooled by water and/or liquid nitrogen) for both the deposition sources and the heated substrate.
2) The amount of impurities in the growing layer is given by the ratio of impinging species (i.e. partial pressure, particles/area/second) and layer growth rate. The lower the gowth rate, the higher the degree of impurities.
3) Substrate temperature governs the sticking of the species on the substrate surface.
4) reaction of deposited material with the impurities (Au vs. Ti)
So the observed effects may be very different for different material systems.
Uday M. Nayef Oxygen comes from any oxygen containing entity (e.g. air or moisture). It's on the surface of everything stored in air - XPS demonstrates this. The laser produces pulsed heating sufficient to convert metal to oxide in the presence of such oxygen containing entities.
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