Refractive index of Ar (Argon)

import lightsmith as ls

# Ar (Argon): Peck and Fisher 1964: n 0.47–2.06 µm; 15 °C
ar = ls.fetch_refractiveindex("main", "Ar", "Peck-15C", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(ar.range_nm)  # (467.9, 2058.7) nm
eps = ar.eps([633])  # complex permittivity

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_597e8c7fab99/lightsmith"
ar = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(ar.source)  # citation and provenance travel with the data

# ... load ar as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=ar)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=468, stop_nm=1000, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength