METHODOLOGY PROTOCOLSpectroscopy & Characterization
UV-Vis Diffuse Reflectance & Tauc Plot Bandgap Derivation
Optical spectroscopy on solid powders and thin films: Kubelka-Munk transformation, direct vs indirect bandgap transitions, and baseline corrections.
Scientific Principles & Procedural Takeaways
1
Transition Exponent: n = 1/2 for direct allowed transitions; n = 2 for indirect phonon-assisted transitions.
2
Inflection Extrapolation: Fit tangent to the point of steepest slope to find the horizontal energy axis intercept.
⚙ Critical Instrument Parameters
Settings & Acquisition Nuances
Integrating sphere reference standard (pure BaSO4 or Spectralon), wavelength scan range (200-900 nm).
⚠️ Critical Bench Pitfall & Troubleshooting
Common Artifacts & Prevention
Drawing tangent fits on raw absorbance instead of the Kubelka-Munk transformed function (F(R)*h*nu)^(1/n).
📥 Starter Practice Datasets
Practice CSV Array
Download Dataset (uvvis_practice_reflectance.csv)Example Practice Data: UV-Vis Diffuse Reflectance (%R) (CSV)
Pedagogical starter diffuse reflectance percentage array across 300 - 800 nm for practicing Kubelka-Munk and Tauc bandgap fits.