I have synthesized silver nano particles/ Guar gum nanocomposite and i have take the Uv-Vis absorbance spectra, it shows the characteristics peak of silver nano particles. This confirms the formation of AgNPs inside the polymer. AgNPs have amazing properties which have altered the electrical, optical properties of original backbone polymer. I want to calculate the optical band gap using Uv-Vis (Tauc plot). but problem is to choose the value of n in tauc plot.
My question is that:
How can we determine the nature of band.
i.e.:
1. Allowed direct
2. Allowed indirect
3. Forbidden direct
4. Forbidden indirect transitions.
Please tell about the nature of band transition, So that we can choose the value of 'n' in Tauc plot.
Thanks in advance
@ Dear vasily
Guar gum polymer is insulator but the addition of AgNPs (which is conductor) alters the electrical properties of this material. So i think they must have band gap
It stay unclear, bandgap of which semiconductor you wish to calculate. Silver is a metal, hence there are no bandgap and no needs in the Tauc plot for silver NPs.
@ Dear vasily
Guar gum polymer is insulator but the addition of AgNPs (which is conductor) alters the electrical properties of this material. So i think they must have band gap
I am more of semiconductor type :)
Will try based on theory : The plot has X (E=hv) and Y(Ahv)1/r
the r gives the 4 conditions you are looking at .
Since yours does not fall under the "solids" category , you have to look amorphous Ag .
I will assume your n = r then how much energy (X-axis) value do you have to pump for the transition to happen is the question !!
May be if you share the plot , I can look at it .
Dear Jagdeep,
Could you please explain the physical reason, why dielectrical polymer becomes a semiconductor in the case of nanocomposite? I mean, what was the band structure before the formation of nanocomposite, and what happens in the contact AgNPs/gum.
But what evidences of semiconductor formation do you have?
And what about the value of dielectric constant for guar gum? How it should affect plasmonic peaks of AgNPs?
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