Inelastic background fitting of Na metal (plasmons)

[Anonymous]

Dear XPS gurus,

I am having issues fitting the inelastic background of a sputter cleaned piece of Na metal with a U4 universal Tougaard background and was wondering if someone had experience on how to fit the background of alkali metals?

I was using the very informative video from the Casa youtube channel as a reference (https://www.youtube.com/watch?v=3QsLq-w4adg&t=416s&ab_channel=CasaXPSCasaSoftware) but realized that the intensity ratio between my first plasmon resonance and the following ones is inadequate (see photo below: there is no surface plasmon contribution on this attempt but adding one does not improve the quality of the background modelling)

Does the close proximity between the Na1s peak and the first plasmon resonance make the universal cross section invalid? The original papers from Tougaard seem to suggest that his cross-section is valid for noble and transition metals but I can’t find any mentions of light metals…

Although the data presented below correspond to a pure Na metal piece, I aim to use a similar fitting strategy to analyse a set of data where a Na containing material is covered by a thin layer of Na metal. I hope to be able to deconvolute the contribution from the Na metal inelastic background and the Na1s peaks of the underlying material.

All suggestions would be very appreciated!

Cheers,

Edouard

 

[DaveXPS]

Hi Edouard

Sorry, but for some reason, I cannot see the image. However materials with strong plasmons ususally need a modified form of the Tougaard bacckground – examples are G, Al and Si in their elemental forms.

You may be better of using a U3 background type in CasaXPS some of the values are always calculated for you, else may be worth using REELS to obtains the cross section data for the metallic Na – see for eample DOI: 10.1016/j.elspec.2009.08.005

• This reply was modified 6 months, 2 weeks ago by DaveXPS.