Optical constants

Refractive index of C₂H₂ (Acetylene)

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

Data: formula 5
Range: 0.5461–0.6708 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: 1.00057
Extinction coefficient k: 0

Permittivity ε₁: 1.00113
Permittivity ε₂: 0

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

Abbe number V_d: —
Chromatic dispersion dn/dλ: -7.76937e-05 µm⁻¹

Group index n_g: 1.00061
Group velocity dispersion: 0.142511 fs²/mm

Dispersion parameter D: -0.777475 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

# C2H2 (Acetylene): Loria 1909: Gas at 0 °C; n 0.529–0.659 µm
c2h2 = ls.fetch_refractiveindex("organic", "acetylene", "Loria", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(c2h2.range_nm)  # (546.1, 670.8) nm
eps = c2h2.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_d33c6bc8da76/lightsmith"
c2h2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(c2h2.source)  # citation and provenance travel with the data

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

# ... load c2h2 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=c2h2)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=547, stop_nm=670, 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 = 1.00054242 + 7.8813626 \times 10^{-6} λ^{- 2.0}

Valid from 0.5461 to 0.6708 µm.

Coefficients as stored

C_i	Value
C1	1.00054242
C2	7.8813626e-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

C2H2 (Acetylene), Loria 1909: Gas at 0 °C; n 0.529–0.659 µm: n and k versus wavelength
λ (µm)	n
0.5461	1.000569
0.546382	1.000569
0.546663	1.000569
0.546945	1.000569
0.547227	1.000569
0.547509	1.000569
0.547792	1.000569
0.548074	1.000569
0.548357	1.000569
0.548639	1.000569
0.548922	1.000569
0.549205	1.000569
0.549488	1.000569
0.549772	1.000568
0.550055	1.000568
0.550339	1.000568
0.550623	1.000568
0.550906	1.000568
0.55119	1.000568
0.551475	1.000568
0.551759	1.000568
0.552043	1.000568
0.552328	1.000568
0.552613	1.000568
0.552898	1.000568
0.553183	1.000568
0.553468	1.000568
0.553753	1.000568
0.554039	1.000568
0.554325	1.000568
0.55461	1.000568
0.554896	1.000568
0.555182	1.000568
0.555469	1.000568
0.555755	1.000568
0.556042	1.000568
0.556328	1.000568
0.556615	1.000568
0.556902	1.000568
0.557189	1.000568
0.557477	1.000568
0.557764	1.000568
0.558052	1.000568
0.558339	1.000568
0.558627	1.000568
0.558915	1.000568
0.559203	1.000568
0.559492	1.000568
0.55978	1.000568
0.560069	1.000568
0.560358	1.000568
0.560647	1.000567
0.560936	1.000567
0.561225	1.000567
0.561514	1.000567
0.561804	1.000567
0.562093	1.000567
0.562383	1.000567
0.562673	1.000567
0.562963	1.000567
0.563253	1.000567
0.563544	1.000567
0.563834	1.000567
0.564125	1.000567
0.564416	1.000567
0.564707	1.000567
0.564998	1.000567
0.56529	1.000567
0.565581	1.000567
0.565873	1.000567
0.566164	1.000567
0.566456	1.000567
0.566748	1.000567
0.567041	1.000567
0.567333	1.000567
0.567625	1.000567
0.567918	1.000567
0.568211	1.000567
0.568504	1.000567
0.568797	1.000567
0.56909	1.000567
0.569384	1.000567
0.569677	1.000567
0.569971	1.000567
0.570265	1.000567
0.570559	1.000567
0.570853	1.000567
0.571147	1.000567
0.571442	1.000567
0.571736	1.000567
0.572031	1.000567
0.572326	1.000566
0.572621	1.000566
0.572916	1.000566
0.573212	1.000566
0.573507	1.000566
0.573803	1.000566
0.574099	1.000566
0.574395	1.000566
0.574691	1.000566
0.574987	1.000566
0.575284	1.000566
0.575581	1.000566
0.575877	1.000566
0.576174	1.000566
0.576471	1.000566
0.576768	1.000566
0.577066	1.000566
0.577363	1.000566
0.577661	1.000566
0.577959	1.000566
0.578257	1.000566
0.578555	1.000566
0.578853	1.000566
0.579152	1.000566
0.57945	1.000566
0.579749	1.000566
0.580048	1.000566
0.580347	1.000566
0.580646	1.000566
0.580946	1.000566
0.581245	1.000566
0.581545	1.000566
0.581845	1.000566
0.582145	1.000566
0.582445	1.000566
0.582745	1.000566
0.583046	1.000566
0.583346	1.000566
0.583647	1.000566
0.583948	1.000566
0.584249	1.000566
0.58455	1.000565
0.584852	1.000565
0.585153	1.000565
0.585455	1.000565
0.585757	1.000565
0.586059	1.000565
0.586361	1.000565
0.586663	1.000565
0.586966	1.000565
0.587268	1.000565
0.587571	1.000565
0.587874	1.000565
0.588177	1.000565
0.588481	1.000565
0.588784	1.000565
0.589088	1.000565
0.589391	1.000565
0.589695	1.000565
0.589999	1.000565
0.590303	1.000565
0.590608	1.000565
0.590912	1.000565
0.591217	1.000565
0.591522	1.000565
0.591827	1.000565
0.592132	1.000565
0.592437	1.000565
0.592743	1.000565
0.593048	1.000565
0.593354	1.000565
0.59366	1.000565
0.593966	1.000565
0.594272	1.000565
0.594579	1.000565
0.594885	1.000565
0.595192	1.000565
0.595499	1.000565
0.595806	1.000565
0.596113	1.000565
0.59642	1.000565
0.596728	1.000565
0.597036	1.000565
0.597343	1.000565
0.597651	1.000564
0.59796	1.000564
0.598268	1.000564
0.598576	1.000564
0.598885	1.000564
0.599194	1.000564
0.599503	1.000564
0.599812	1.000564
0.600121	1.000564
0.600431	1.000564
0.60074	1.000564
0.60105	1.000564
0.60136	1.000564
0.60167	1.000564
0.60198	1.000564
0.60229	1.000564
0.602601	1.000564
0.602912	1.000564
0.603222	1.000564
0.603533	1.000564
0.603845	1.000564
0.604156	1.000564
0.604468	1.000564
0.604779	1.000564
0.605091	1.000564
0.605403	1.000564
0.605715	1.000564
0.606027	1.000564
0.60634	1.000564
0.606653	1.000564
0.606965	1.000564
0.607278	1.000564
0.607591	1.000564
0.607905	1.000564
0.608218	1.000564
0.608532	1.000564
0.608845	1.000564
0.609159	1.000564
0.609473	1.000564
0.609788	1.000564
0.610102	1.000564
0.610417	1.000564
0.610731	1.000564
0.611046	1.000564
0.611361	1.000564
0.611676	1.000563
0.611992	1.000563
0.612307	1.000563
0.612623	1.000563
0.612939	1.000563
0.613255	1.000563
0.613571	1.000563
0.613888	1.000563
0.614204	1.000563
0.614521	1.000563
0.614838	1.000563
0.615155	1.000563
0.615472	1.000563
0.615789	1.000563
0.616107	1.000563
0.616424	1.000563
0.616742	1.000563
0.61706	1.000563
0.617378	1.000563
0.617697	1.000563
0.618015	1.000563
0.618334	1.000563
0.618652	1.000563
0.618971	1.000563
0.619291	1.000563
0.61961	1.000563
0.619929	1.000563
0.620249	1.000563
0.620569	1.000563
0.620889	1.000563
0.621209	1.000563
0.621529	1.000563
0.62185	1.000563
0.62217	1.000563
0.622491	1.000563
0.622812	1.000563
0.623133	1.000563
0.623454	1.000563
0.623776	1.000563
0.624097	1.000563
0.624419	1.000563
0.624741	1.000563
0.625063	1.000563
0.625386	1.000563
0.625708	1.000563
0.626031	1.000563
0.626353	1.000563
0.626676	1.000562
0.626999	1.000562
0.627323	1.000562
0.627646	1.000562
0.62797	1.000562
0.628294	1.000562
0.628617	1.000562
0.628942	1.000562
0.629266	1.000562
0.62959	1.000562
0.629915	1.000562
0.63024	1.000562
0.630565	1.000562
0.63089	1.000562
0.631215	1.000562
0.631541	1.000562
0.631866	1.000562
0.632192	1.000562
0.632518	1.000562
0.632844	1.000562
0.63317	1.000562
0.633497	1.000562
0.633823	1.000562
0.63415	1.000562
0.634477	1.000562
0.634804	1.000562
0.635132	1.000562
0.635459	1.000562
0.635787	1.000562
0.636114	1.000562
0.636442	1.000562
0.636771	1.000562
0.637099	1.000562
0.637427	1.000562
0.637756	1.000562
0.638085	1.000562
0.638414	1.000562
0.638743	1.000562
0.639072	1.000562
0.639402	1.000562
0.639732	1.000562
0.640061	1.000562
0.640391	1.000562
0.640722	1.000562
0.641052	1.000562
0.641382	1.000562
0.641713	1.000562
0.642044	1.000562
0.642375	1.000562
0.642706	1.000561
0.643038	1.000561
0.643369	1.000561
0.643701	1.000561
0.644033	1.000561
0.644365	1.000561
0.644697	1.000561
0.645029	1.000561
0.645362	1.000561
0.645695	1.000561
0.646028	1.000561
0.646361	1.000561
0.646694	1.000561
0.647027	1.000561
0.647361	1.000561
0.647695	1.000561
0.648029	1.000561
0.648363	1.000561
0.648697	1.000561
0.649032	1.000561
0.649366	1.000561
0.649701	1.000561
0.650036	1.000561
0.650371	1.000561
0.650707	1.000561
0.651042	1.000561
0.651378	1.000561
0.651714	1.000561
0.65205	1.000561
0.652386	1.000561
0.652722	1.000561
0.653059	1.000561
0.653395	1.000561
0.653732	1.000561
0.654069	1.000561
0.654407	1.000561
0.654744	1.000561
0.655082	1.000561
0.655419	1.000561
0.655757	1.000561
0.656095	1.000561
0.656434	1.000561
0.656772	1.000561
0.657111	1.000561
0.65745	1.000561
0.657789	1.000561
0.658128	1.000561
0.658467	1.000561
0.658807	1.000561
0.659146	1.000561
0.659486	1.000561
0.659826	1.000561
0.660166	1.000561
0.660507	1.00056
0.660847	1.00056
0.661188	1.00056
0.661529	1.00056
0.66187	1.00056
0.662211	1.00056
0.662553	1.00056
0.662894	1.00056
0.663236	1.00056
0.663578	1.00056
0.66392	1.00056
0.664262	1.00056
0.664605	1.00056
0.664948	1.00056
0.66529	1.00056
0.665633	1.00056
0.665977	1.00056
0.66632	1.00056
0.666664	1.00056
0.667007	1.00056
0.667351	1.00056
0.667695	1.00056
0.66804	1.00056
0.668384	1.00056
0.668729	1.00056
0.669073	1.00056
0.669418	1.00056
0.669763	1.00056
0.670109	1.00056
0.670454	1.00056
0.6708	1.00056

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: —

C₂H₂ (Acetylene): all datasets

Loria 1909: Gas at 0 °C; n 0.529–0.659 µm n 0.5461–0.6708 µm default

About C2H2 (Acetylene)

Acetylene (C₂H₂), often represented as HC≡CH, is a hydrocarbon and the simplest alkyne. It's a colorless gas under normal conditions and has a distinctive garlic-like odor. Acetylene is a key component for oxy-acetylene welding due to its ability to produce an extremely hot flame when combined with oxygen. This gas is also utilized in the production of various organic chemicals and the synthesis of polyethylene plastics and acrylics. Its linear structure confers a high degree of unsaturation, making it reactive in many chemical processes.

More about C2H2 (Acetylene) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/organic/C2H2 - acetylene/nk/Loria.yml
ID: ds_d33c6bc8da76
API: /v1/datasets/ds_d33c6bc8da76

Plot