Computed Optical Properties

The optical properties are computed for a wavelength range of 200 to 2000 nm using state-of-the-art numerical methods combined with experimental data.

Complex Refractive Indices

The complex refractive indices are derived using the modeling framework described in Martikainen et al. 2023, ApJS, along with the measured particle size distribution and diffuse reflectance spectrum.
The model assumes Gaussian random spheres (GRS) as the shapes of the particles.

• Uncertainties: A maximum error of 15% in the measured reflectance is assumed over the entire wavelength range (200–2000 nm).
• Refinement: The real part of the complex refractive index is further fine-tuned using the modeling approach detailed in Martikainen et al. 2025, MNRAS.

Extinction Efficiencies, Single-Scattering Albedos, Asymmetry Factors, Extinction Cross-Sections, and Phase Matrices

These optical properties are retrieved using a hexahedra database (Saito et al. 2021, JAS), and further averaged over the measured particle size distribution as shown by Martikainen et al. 2025, MNRAS.

Output Details

1. OpticalPropertiesXXX:
   • Contains bulk extinction efficiencies, single-scattering albedos, asymmetry factors, and extinction cross-sections for the wavelength range of 200–2000 nm.
   • XXX refers to the name of the sample.
2. avgP_YYY.dat:
   • Provides the bulk scattering phase matrix for a specific wavelength.
   • YYY indicates the wavelength in nanometers.

Structure of avgP_YYY.dat
The file comprises 498 lines corresponding to scattering angles, with the following 7 columns:

1. Scattering angle (degrees)
2. P11
3. P12
4. P22
5. P33
6. P43
7. P44

References:

• Saito et al. 2021, JAS, 78, 2089
• Martikainen et al. 2023, ApJS,
• Martikainen et al. 2025, MNRAS, accepted (to be added later)