Shortwave imaginary refractive index of alumina aerosols.

This repository contains the following datasets and supporting materials:

1) Alumina_Refractive_Index_1nm.csv

Description: Complex refractive index (n and k) at 1 nm resolution.
Wavelength Range: 10–100,000 nm. Refractive indices between 120–6500 nm are derived from Urbach-tail fits of photoacoustic spectrometry (PAS) data; values outside this range are from Tropf and Thomas (1997).
Columns:
• wavelength (nm)
• k — imaginary part of refractive index
• k_25 — 25th percentile of k from PAS-derived fits
• k_75 — 75th percentile of k from PAS-derived fits

2) Alumina_Refractive_Index_PAS.csv

Description: Imaginary refractive index (k) retrieved from in situ measurements and Mie theory inversions (Sumlin et al., 2016). Absorption and scattering coefficients were measured with integrated photoacoustic spectrometers (Upadhyay et al., 2025), and particle number size distributions with a scanning mobility particle sizer and an aerodynamic aerosol classifier.
Columns:
• particle_type — spherical α-phase, irregular α-phase, irregular γ-phase
• wavelength (nm) — 375, 405, 532, 721, and 1047 nm.
• N — number of data points
• k_25 — 25th percentile
• k_median — median value
• k_75 — 75th percentile

3) Alumina_Refractive_Index_EELS.csv

Description: Imaginary refractive index (k) measured for individual particles using STEM–EELS (Scanning Transmission Electron Microscopy–Electron Energy Loss Spectroscopy) of spherical α-phase alumina particles.
Columns:
• wavelength (nm)
• k_1 to k_10 — k values for ten individual particles

4) EELS_Anlysis (folder)

• Contains raw EELS spectra (subfolder: particles) and processed data (subfolder: data).
• A PowerPoint presentation (EELS_SI.pptx) provides a comprehensive analysis of the EELS measurements, including an exemplar particle with a corresponding HAADF image, the extraction of the refractive index (k) via Kramers–Kronig analysis (KKA), an assessment of the influence of zero-loss peak (ZLP) tail cutoff on the derived optical constants, and the identification of oxygen-vacancy defects through the evaluation of the imaginary component of the refractive index.
• A separate codes folder includes the analysis scripts used to process the EELS data and generate figures.