Documentation & Math

Multi-File Workflow

This tool allows you to analyze multiple datasets simultaneously.

• Import: Upload one or multiple .csv/.txt files at once with Add Files or by drag and drop.
• Select to Edit: In the File List (sidebar), click the icon next to a file to make it "Active".
• Adjust: Switch to the Analysis tab in the sidebar. Any changes to units, thickness, or fit range apply only to the active file.
• Compare: Use the checkboxes in the File List to hide/show specific plots.

---

Data

Data can be exported in several ways.

• CSV: Raw spectra and calculated Tauc plots can be saved as CSV with the Download CSV button.
• Report: The PDF Report saves a timestamped PDF with all graphs and the fit results.
• Plots: Plots can be zoomed and saved as PNG; see the toolbar in the top right of each chart.

---

Input Scaling

Reflectance and transmittance are accepted either as percent (0–100) or as a fraction (0–1). The scale is detected per file from the maximum Y value (> 1.5 → percent) and shown in the Analysis tab.

Absorbance & Transmittance Mode

Calculates the absorption coefficient (α) for films or liquids.

• Transmittance is converted as A = −log10(T), with T as a fraction.
• α: α = (2.303 × A) / d
  (where d is the sample thickness in cm)

Reflectance Mode (Kubelka–Munk)

Calculates F(R) for powders and diffuse surfaces.

• F(R): F(R) = (1 − R)2 / (2 × R)
• In this mode the ordinate is (F(R)·hν)1/n, not (αhν)1/n; thickness is unused.

Tauc Equations

Fit Quality

A fit is reported only when it uses at least 3 points, has a non-degenerate slope, and yields an E_g = −c/m that is finite, positive and inside (or just beyond) the data range. Rows with R² < 0.99 are dimmed. n is the number of points entering the regression — a high R² obtained on 4 points is not a good fit.

Auto-Detect

The "Magic Wand" button in the Analysis tab selects the top 40% of the energy range, where the fundamental absorption edge usually lies. It is a starting point, not a substitute for inspection.