Hi,
We're trying to model the optical properties of a biosensor, and one key parameter seems to be the thin film between the glass surface of the sensor, and the self-assembled gold monolayer. This film, in our case, is a layer of 3-(amino-propyl)trimethoxysilanes. According to our model, this film does have an effect on the system. We've tried to model it as a constant index of refraction, but the curves become skewed in a way that tells me that this film should be modeled with some dispersion.
I've seen a lot of material models such as the Sellmeir equation for predicting refractive index, but I have very little sense on when to use what model. Is there a model that might be best for guesstimating the dispersion in a thin film of silanes such as this? Any tips on what considerations even go into choosing a material model equation?
Thanks
Just to followup:
Here's the dispersion in a glass sample that was modeled with Sellmeir:
http://www.filmetrics.com/refractive-index-database/Schott+LLF1
My question is, did they know a-priori that Sellmeir is a good way to model this, or did they have to do experimental fits before making this deterimination? If they had measured the index at say lambda = 530nm, could they have extrapolated via Sellmeir to get a good approximation of this curve without doing any measurements?
I read an ellipsometry guide, and it seems like the fitting is fairly lax. IE some people even use impossible materials (ie violation of kramer's kronig) in ellipsometry models.
Thanks Sarka. We were able to figure it out by fudging parameters. Our program is fully dispersive so we didn't need to do discrete wavelengths. I appreciate your help
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