Optical constants

Refractive index of CH₄ (Methane)

Loria 1909: Gas at 0 °C; n 0.529–0.659 µm

Data: formula 5
Range: 0.529–0.6585 µm
Temperature: 273.15 K
State: gas
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.00044
Extinction coefficient k: 0

Permittivity ε₁: 1.00089
Permittivity ε₂: 0

Absorption coefficient α: 0 cm⁻¹
Penetration depth δ = λ/(2πk): — nm

Abbe number V_d: —
Chromatic dispersion dn/dλ: -6.05243e-05 µm⁻¹

Group index n_g: 1.00048
Group velocity dispersion: 0.111018 fs²/mm

Dispersion parameter D: -0.605662 ps/(nm·km)
Photon energy: 2.11001 eV

ε = (n + ik)², α = 4πk/λ, n_g = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith

import lightsmith as ls

# CH4 (Methane): Loria 1909: Gas at 0 °C; n 0.529–0.659 µm
ch4 = ls.fetch_refractiveindex("organic", "methane", "Loria", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(ch4.range_nm)  # (529, 658.5) nm
eps = ch4.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_a7e210da7443/lightsmith"
ch4 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(ch4.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (methane/loria-1909).

# ... load ch4 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=ch4)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=529, stop_nm=658, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength

Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).

Materials guide Open a sphere of it in Studio Quick start Ask the community

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Dispersion formula

Cauchy (formula 5), λ in µm

n = 1.00042607 + 6.1396687 \times 10^{-6} λ^{- 2.0}

Valid from 0.529 to 0.6585 µm.

Coefficients as stored

C_i	Value
C1	1.00042607
C2	6.1396687e-06
C3	-2.0

Comments and conditions

Standard conditions. 0 °C, 760 torr (101.325 kPa).

Conditions

temperature: 273.15 K
pressure: 101325

References

S. Loria. Über die Dispersion des Lichtes in gasförmigen Kohlenwasserstoffen. Annalen der Physik 334, 605-622 (1909) (in German).

doi:10.1002/andp.19093340809 Über die Dispersion des Lichtes in gasförmigen Kohlenwasserstoffen, Annalen der Physik (1909)

Cite

Stanisław Loria. Über die Dispersion des Lichtes in gasförmigen Kohlenwasserstoffen. Annalen der Physik, 334, 605-622 (1909), doi:10.1002/andp.19093340809; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

Computed on 400 wavelengths, the same grid as the API and the library

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

CH4 (Methane), Loria 1909: Gas at 0 °C; n 0.529–0.659 µm: n and k versus wavelength
λ (µm)	n
0.529	1.000448
0.52929	1.000448
0.529581	1.000448
0.529872	1.000448
0.530163	1.000448
0.530454	1.000448
0.530745	1.000448
0.531036	1.000448
0.531328	1.000448
0.531619	1.000448
0.531911	1.000448
0.532203	1.000448
0.532495	1.000448
0.532788	1.000448
0.53308	1.000448
0.533373	1.000448
0.533666	1.000448
0.533959	1.000448
0.534252	1.000448
0.534545	1.000448
0.534838	1.000448
0.535132	1.000448
0.535426	1.000447
0.53572	1.000447
0.536014	1.000447
0.536308	1.000447
0.536602	1.000447
0.536897	1.000447
0.537192	1.000447
0.537487	1.000447
0.537782	1.000447
0.538077	1.000447
0.538372	1.000447
0.538668	1.000447
0.538964	1.000447
0.539259	1.000447
0.539556	1.000447
0.539852	1.000447
0.540148	1.000447
0.540445	1.000447
0.540741	1.000447
0.541038	1.000447
0.541335	1.000447
0.541632	1.000447
0.54193	1.000447
0.542227	1.000447
0.542525	1.000447
0.542823	1.000447
0.543121	1.000447
0.543419	1.000447
0.543717	1.000447
0.544016	1.000447
0.544314	1.000447
0.544613	1.000447
0.544912	1.000447
0.545211	1.000447
0.54551	1.000447
0.54581	1.000447
0.54611	1.000447
0.546409	1.000447
0.546709	1.000447
0.547009	1.000447
0.54731	1.000447
0.54761	1.000447
0.547911	1.000447
0.548212	1.000446
0.548512	1.000446
0.548814	1.000446
0.549115	1.000446
0.549416	1.000446
0.549718	1.000446
0.55002	1.000446
0.550322	1.000446
0.550624	1.000446
0.550926	1.000446
0.551228	1.000446
0.551531	1.000446
0.551834	1.000446
0.552137	1.000446
0.55244	1.000446
0.552743	1.000446
0.553047	1.000446
0.55335	1.000446
0.553654	1.000446
0.553958	1.000446
0.554262	1.000446
0.554566	1.000446
0.554871	1.000446
0.555175	1.000446
0.55548	1.000446
0.555785	1.000446
0.55609	1.000446
0.556395	1.000446
0.556701	1.000446
0.557006	1.000446
0.557312	1.000446
0.557618	1.000446
0.557924	1.000446
0.558231	1.000446
0.558537	1.000446
0.558844	1.000446
0.55915	1.000446
0.559457	1.000446
0.559764	1.000446
0.560072	1.000446
0.560379	1.000446
0.560687	1.000446
0.560995	1.000446
0.561303	1.000446
0.561611	1.000446
0.561919	1.000446
0.562228	1.000445
0.562536	1.000445
0.562845	1.000445
0.563154	1.000445
0.563463	1.000445
0.563772	1.000445
0.564082	1.000445
0.564392	1.000445
0.564701	1.000445
0.565011	1.000445
0.565322	1.000445
0.565632	1.000445
0.565942	1.000445
0.566253	1.000445
0.566564	1.000445
0.566875	1.000445
0.567186	1.000445
0.567498	1.000445
0.567809	1.000445
0.568121	1.000445
0.568433	1.000445
0.568745	1.000445
0.569057	1.000445
0.569369	1.000445
0.569682	1.000445
0.569995	1.000445
0.570308	1.000445
0.570621	1.000445
0.570934	1.000445
0.571247	1.000445
0.571561	1.000445
0.571875	1.000445
0.572189	1.000445
0.572503	1.000445
0.572817	1.000445
0.573131	1.000445
0.573446	1.000445
0.573761	1.000445
0.574076	1.000445
0.574391	1.000445
0.574706	1.000445
0.575022	1.000445
0.575337	1.000445
0.575653	1.000445
0.575969	1.000445
0.576285	1.000445
0.576602	1.000445
0.576918	1.000445
0.577235	1.000444
0.577552	1.000444
0.577869	1.000444
0.578186	1.000444
0.578504	1.000444
0.578821	1.000444
0.579139	1.000444
0.579457	1.000444
0.579775	1.000444
0.580093	1.000444
0.580412	1.000444
0.58073	1.000444
0.581049	1.000444
0.581368	1.000444
0.581687	1.000444
0.582007	1.000444
0.582326	1.000444
0.582646	1.000444
0.582966	1.000444
0.583286	1.000444
0.583606	1.000444
0.583926	1.000444
0.584247	1.000444
0.584568	1.000444
0.584888	1.000444
0.585209	1.000444
0.585531	1.000444
0.585852	1.000444
0.586174	1.000444
0.586496	1.000444
0.586818	1.000444
0.58714	1.000444
0.587462	1.000444
0.587785	1.000444
0.588107	1.000444
0.58843	1.000444
0.588753	1.000444
0.589076	1.000444
0.5894	1.000444
0.589723	1.000444
0.590047	1.000444
0.590371	1.000444
0.590695	1.000444
0.591019	1.000444
0.591344	1.000444
0.591668	1.000444
0.591993	1.000444
0.592318	1.000444
0.592643	1.000444
0.592969	1.000444
0.593294	1.000444
0.59362	1.000443
0.593946	1.000443
0.594272	1.000443
0.594598	1.000443
0.594924	1.000443
0.595251	1.000443
0.595578	1.000443
0.595905	1.000443
0.596232	1.000443
0.596559	1.000443
0.596887	1.000443
0.597214	1.000443
0.597542	1.000443
0.59787	1.000443
0.598198	1.000443
0.598527	1.000443
0.598855	1.000443
0.599184	1.000443
0.599513	1.000443
0.599842	1.000443
0.600171	1.000443
0.600501	1.000443
0.600831	1.000443
0.60116	1.000443
0.60149	1.000443
0.601821	1.000443
0.602151	1.000443
0.602481	1.000443
0.602812	1.000443
0.603143	1.000443
0.603474	1.000443
0.603806	1.000443
0.604137	1.000443
0.604469	1.000443
0.6048	1.000443
0.605132	1.000443
0.605465	1.000443
0.605797	1.000443
0.60613	1.000443
0.606462	1.000443
0.606795	1.000443
0.607128	1.000443
0.607462	1.000443
0.607795	1.000443
0.608129	1.000443
0.608463	1.000443
0.608797	1.000443
0.609131	1.000443
0.609465	1.000443
0.6098	1.000443
0.610135	1.000443
0.61047	1.000443
0.610805	1.000443
0.61114	1.000443
0.611475	1.000442
0.611811	1.000442
0.612147	1.000442
0.612483	1.000442
0.612819	1.000442
0.613156	1.000442
0.613492	1.000442
0.613829	1.000442
0.614166	1.000442
0.614503	1.000442
0.614841	1.000442
0.615178	1.000442
0.615516	1.000442
0.615854	1.000442
0.616192	1.000442
0.61653	1.000442
0.616868	1.000442
0.617207	1.000442
0.617546	1.000442
0.617885	1.000442
0.618224	1.000442
0.618564	1.000442
0.618903	1.000442
0.619243	1.000442
0.619583	1.000442
0.619923	1.000442
0.620263	1.000442
0.620604	1.000442
0.620944	1.000442
0.621285	1.000442
0.621626	1.000442
0.621968	1.000442
0.622309	1.000442
0.622651	1.000442
0.622993	1.000442
0.623335	1.000442
0.623677	1.000442
0.624019	1.000442
0.624362	1.000442
0.624704	1.000442
0.625047	1.000442
0.62539	1.000442
0.625734	1.000442
0.626077	1.000442
0.626421	1.000442
0.626765	1.000442
0.627109	1.000442
0.627453	1.000442
0.627798	1.000442
0.628142	1.000442
0.628487	1.000442
0.628832	1.000442
0.629177	1.000442
0.629523	1.000442
0.629868	1.000442
0.630214	1.000442
0.63056	1.000442
0.630906	1.000441
0.631253	1.000441
0.631599	1.000441
0.631946	1.000441
0.632293	1.000441
0.63264	1.000441
0.632987	1.000441
0.633335	1.000441
0.633682	1.000441
0.63403	1.000441
0.634378	1.000441
0.634726	1.000441
0.635075	1.000441
0.635424	1.000441
0.635772	1.000441
0.636121	1.000441
0.636471	1.000441
0.63682	1.000441
0.63717	1.000441
0.637519	1.000441
0.637869	1.000441
0.638219	1.000441
0.63857	1.000441
0.63892	1.000441
0.639271	1.000441
0.639622	1.000441
0.639973	1.000441
0.640325	1.000441
0.640676	1.000441
0.641028	1.000441
0.64138	1.000441
0.641732	1.000441
0.642084	1.000441
0.642436	1.000441
0.642789	1.000441
0.643142	1.000441
0.643495	1.000441
0.643848	1.000441
0.644202	1.000441
0.644555	1.000441
0.644909	1.000441
0.645263	1.000441
0.645618	1.000441
0.645972	1.000441
0.646327	1.000441
0.646681	1.000441
0.647036	1.000441
0.647392	1.000441
0.647747	1.000441
0.648103	1.000441
0.648458	1.000441
0.648814	1.000441
0.649171	1.000441
0.649527	1.000441
0.649883	1.000441
0.65024	1.000441
0.650597	1.000441
0.650954	1.000441
0.651312	1.000441
0.651669	1.000441
0.652027	1.000441
0.652385	1.00044
0.652743	1.00044
0.653101	1.00044
0.65346	1.00044
0.653819	1.00044
0.654178	1.00044
0.654537	1.00044
0.654896	1.00044
0.655255	1.00044
0.655615	1.00044
0.655975	1.00044
0.656335	1.00044
0.656696	1.00044
0.657056	1.00044
0.657417	1.00044
0.657778	1.00044
0.658139	1.00044
0.6585	1.00044

Optical transmission calculator

Free-standing sample in vacuum, normal incidence

Transmittance T: —
Reflectance R: —

Fresnel reflection calculator

R_p: —
R_s: —
R = (R_p+R_s)/2: —
Phase φ_p: —
Phase φ_s: —
Brewster angle θ_B: —
Critical angle θ_C: —

CH₄ (Methane): all datasets

Gas

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Solid

About CH4 (Methane)

Methane (CH₄) is the simplest alkane and is a colorless, odorless gas under standard conditions. It is the primary constituent of natural gas and is notable for being a potent greenhouse gas. In the environment, methane is produced during the anaerobic decomposition of organic matter, such as in wetlands, ruminant digestion, and landfills. It can also be found in various industrial processes and is used as a fuel for heating and electricity generation. In the realm of optics, methane's refractive properties might be of interest, especially when considering its potential presence in gaseous atmospheres of extraterrestrial bodies.

More about CH4 (Methane) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/organic/CH4 - methane/nk/Loria.yml
ID: ds_a7e210da7443
API: /v1/datasets/ds_a7e210da7443

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