I have deposited Ag nanoparticle on exfoliated MoS2 by using electron beam evaporation method.
And the results are as below;
Before the Ag nanoparticle deposition, the binding energies are such that: Mo3d 3/2 = 232.55 eV, Mo3d 5/2 = 229.4 eV and S2p 1/2 = 163.47 eV, S2p 3/2 = 162.27 eV.
And after the Ag nanoparticle deposition, the binding energies are such that: Mo3d 3/2 = 232.68 eV, Mo3d 5/2 = 229.53 eV and S2p 1/2 = 163.58 eV, S2p 3/2 = 162.36 eV.
So that, the binding energy for both species increases by ~0.12 eV.
My sincere and humble questions are;
(note- the adventitious carbon C1s BE peak for both measurements are calibrated at 284.8 eV.)
Dear Yan, what about the binding energy of the Ag NPs - is it still metallic Ag, i.e. around 368.2 eV. And I guess you meant that C1s is at 284.8 eV ... Of course, Ag has a large affinity towards S, but I doubt whether or not it is larger compared to Mo - did you checked the standard enthalpy of formation for Ag2S and MoS2? I guess that the latter is larger ... Good luck, Dirk
Dear Profs. Dirk Luetzenkirchen-Hecht , first of all, thank you for your reply.
The C1s peak is at 284.3 eV, ( thanks for correction).
The BE for Ag NPs are around 368.3 eV as you suggested with the small loss feature bumb around 372 eV. Because of the XPS measurement configuration, the detectable region of Ag-MoS2 interface is quite narrow and the XPS signals for Ag mainly come from open Ag NPs surface.
I am really curious about the increase in binding energy of Mo and S.
That's true - did you check the enthalpies of formation for the two compounds?
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