Refractive index of Hydrogenated amorphous carbon

import lightsmith as ls

# Hydrogenated amorphous carbon: Smith 1984: Annealed at 650 °; n,k 0.261–0.827 µm
hac = ls.fetch_refractiveindex("other", "HAC", "Smith-Ta650C", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(hac.range_nm)  # (261, 827) nm
eps = hac.eps([633])  # complex permittivity

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_0ee2275aae3d/lightsmith"
hac = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(hac.source)  # citation and provenance travel with the data

# ... load hac as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=hac)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=827, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength