Undergrad Colloid complex refractive index from UV-vis spec

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SUMMARY

The discussion focuses on using the damped wave approximation in conjunction with Beer’s Law to spectroscopically determine the complex refractive index of colloids. The equation for absorbance, expressed as Absorbance = exp(-2πkx/λ) = ecl, is highlighted as a method for extracting the extinction coefficient (k) as a function of wavelength. Fitting a series of Lorentz oscillators to the extracted data can yield the refractive index (n). However, a strong understanding of the material's physics is essential to avoid inaccurate results.

PREREQUISITES
  • Understanding of Beer’s Law in spectroscopy
  • Knowledge of the damped wave approximation
  • Familiarity with Lorentz oscillators and their application
  • Basic principles of complex refractive index
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  • Research the application of Beer’s Law in UV-Vis spectroscopy
  • Study the damped wave approximation in optical physics
  • Learn about fitting techniques for Lorentz oscillators
  • Explore methods for calculating complex refractive indices in colloidal systems
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Researchers in optical physics, materials scientists, and anyone involved in the spectroscopic analysis of colloidal systems will benefit from this discussion.

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TL;DR
Can I determine the complex refractive index (n + ik) of a colloid via UV-vis spectroscopy?
Hi everyone,

I am wondering, can I use the damped wave approximation for light travelling through a medium along with Beers law to spectroscopically determine a colloid complex refractive index.
Thanks!

Absorbance = exp (- 2πkx/λ) = ecl
 
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I think it's possible. You could extract k as a function of wavelength, and then fit a series of Lorentz oscillators to it. This would then give you n. Beware though, if you don't understand the physics of your material, then I'd say that you could end up with numbers that aren't a good match to reality.
 
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