Optical constants

Refractive index of LiF (Lithium fluoride)

Li 1976: n 0.10–11 µm

Data: formula 1
Range: 0.1–11 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.39215
Extinction coefficient k: 0

Permittivity ε₁: 1.93807
Permittivity ε₂: 0

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

Abbe number V_d: 97.295
Chromatic dispersion dn/dλ: -0.0211396 µm⁻¹

Group index n_g: 1.40457
Group velocity dispersion: 32.685 fs²/mm

Dispersion parameter D: -178.314 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

# LiF (Lithium fluoride): Li 1976: n 0.10–11 µm
lif = ls.fetch_refractiveindex("main", "LiF", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(lif.range_nm)  # (100, 11000) nm
eps = lif.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_3e311e71e95f/lightsmith"
lif = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(lif.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (lif/li-1976).

# ... load lif as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=lif)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, 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"]).

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_3e311e71e95f/lightsmith?model=drude_lorentz"
lif_dl = ls.DrudeLorentz.model_validate(json.load(urllib.request.urlopen(url)))

A dispersive Drude–Lorentz model for time-domain solvers.

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

Sellmeier (formula 1), λ in µm

n^{2} - 1 = \frac{0.92549 λ^{2}}{λ^{2} - {0.07376}^{2}} + \frac{6.96747 λ^{2}}{λ^{2} - {32.79}^{2}}

Valid from 0.1 to 11.0 µm.

Coefficients as stored

C_i	Value
C1	0.0
C2	0.92549
C3	0.07376
C4	6.96747
C5	32.79

Comments and conditions

297 K (24 °C).

References

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 5, 329-528 (1976) and references therein.
* Sellmeier formula is derived by critical analysis of experimental data from several sources.

doi:10.1063/1.555536 Refractive index of alkali halides and its wavelength and temperature derivatives, Journal of Physical and Chemical Reference Data (1976)

Cite

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data, 5, 329-528 (1976), doi:10.1063/1.555536; 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

LiF (Lithium fluoride), Li 1976: n 0.10–11 µm: n and k versus wavelength
λ (µm)	n
0.1	1.74062
0.101185	1.724784
0.102384	1.709992
0.103597	1.696145
0.104825	1.683159
0.106067	1.670956
0.107324	1.659472
0.108596	1.648646
0.109883	1.638425
0.111185	1.628763
0.112503	1.619616
0.113836	1.610946
0.115185	1.60272
0.11655	1.594904
0.117931	1.587472
0.119328	1.580398
0.120743	1.573657
0.122173	1.567228
0.123621	1.561092
0.125086	1.55523
0.126568	1.549627
0.128068	1.544266
0.129586	1.539133
0.131122	1.534216
0.132675	1.529502
0.134248	1.52498
0.135839	1.52064
0.137448	1.516472
0.139077	1.512467
0.140725	1.508617
0.142393	1.504914
0.14408	1.50135
0.145788	1.497919
0.147515	1.494614
0.149263	1.49143
0.151032	1.48836
0.152822	1.4854
0.154633	1.482544
0.156465	1.479787
0.15832	1.477126
0.160196	1.474556
0.162094	1.472073
0.164015	1.469674
0.165959	1.467355
0.167925	1.465112
0.169915	1.462942
0.171929	1.460843
0.173966	1.458811
0.176028	1.456845
0.178114	1.454941
0.180224	1.453096
0.18236	1.45131
0.184521	1.449578
0.186708	1.447901
0.18892	1.446274
0.191159	1.444697
0.193424	1.443167
0.195717	1.441684
0.198036	1.440244
0.200383	1.438848
0.202757	1.437492
0.20516	1.436176
0.207591	1.434899
0.210051	1.433658
0.21254	1.432453
0.215059	1.431283
0.217608	1.430146
0.220186	1.429042
0.222796	1.427968
0.225436	1.426925
0.228107	1.425911
0.23081	1.424925
0.233546	1.423966
0.236313	1.423034
0.239114	1.422127
0.241947	1.421245
0.244814	1.420388
0.247715	1.419553
0.250651	1.418741
0.253621	1.417951
0.256627	1.417182
0.259668	1.416433
0.262745	1.415704
0.265859	1.414995
0.269009	1.414304
0.272197	1.413632
0.275423	1.412977
0.278686	1.412339
0.281989	1.411718
0.285331	1.411112
0.288712	1.410523
0.292133	1.409948
0.295595	1.409389
0.299098	1.408843
0.302642	1.408312
0.306229	1.407794
0.309858	1.407289
0.31353	1.406796
0.317245	1.406316
0.321004	1.405849
0.324808	1.405392
0.328657	1.404948
0.332552	1.404514
0.336493	1.404091
0.340481	1.403678
0.344515	1.403275
0.348598	1.402882
0.352729	1.402499
0.356909	1.402125
0.361138	1.40176
0.365418	1.401404
0.369748	1.401057
0.37413	1.400718
0.378564	1.400386
0.38305	1.400063
0.387589	1.399748
0.392182	1.399439
0.396829	1.399138
0.401532	1.398844
0.40629	1.398557
0.411105	1.398277
0.415977	1.398003
0.420906	1.397735
0.425894	1.397473
0.430941	1.397218
0.436048	1.396968
0.441215	1.396724
0.446444	1.396485
0.451734	1.396251
0.457087	1.396023
0.462504	1.3958
0.467985	1.395581
0.47353	1.395367
0.479142	1.395158
0.48482	1.394954
0.490565	1.394753
0.496379	1.394557
0.502261	1.394365
0.508213	1.394177
0.514235	1.393993
0.520329	1.393813
0.526495	1.393636
0.532734	1.393463
0.539047	1.393293
0.545435	1.393127
0.551899	1.392963
0.558439	1.392803
0.565057	1.392646
0.571753	1.392492
0.578528	1.392341
0.585384	1.392192
0.592321	1.392046
0.59934	1.391903
0.606443	1.391762
0.613629	1.391624
0.620901	1.391488
0.628259	1.391354
0.635704	1.391222
0.643237	1.391093
0.65086	1.390965
0.658572	1.39084
0.666377	1.390716
0.674274	1.390594
0.682264	1.390474
0.690349	1.390355
0.69853	1.390238
0.706808	1.390123
0.715184	1.390009
0.723659	1.389896
0.732234	1.389785
0.740911	1.389674
0.749691	1.389566
0.758576	1.389458
0.767565	1.389351
0.776661	1.389245
0.785864	1.38914
0.795177	1.389036
0.8046	1.388933
0.814135	1.388831
0.823783	1.388729
0.833545	1.388628
0.843423	1.388528
0.853418	1.388428
0.863531	1.388329
0.873764	1.38823
0.884118	1.388131
0.894595	1.388033
0.905197	1.387935
0.915924	1.387837
0.926778	1.387739
0.93776	1.387641
0.948873	1.387543
0.960117	1.387446
0.971495	1.387348
0.983008	1.38725
0.994656	1.387152
1.00644	1.387054
1.01837	1.386955
1.03044	1.386856
1.04265	1.386756
1.055	1.386656
1.06751	1.386556
1.08016	1.386455
1.09296	1.386353
1.10591	1.386251
1.11901	1.386147
1.13228	1.386043
1.14569	1.385938
1.15927	1.385833
1.17301	1.385726
1.18691	1.385618
1.20097	1.385509
1.21521	1.385399
1.22961	1.385287
1.24418	1.385175
1.25892	1.38506
1.27384	1.384945
1.28894	1.384828
1.30421	1.384709
1.31966	1.384589
1.3353	1.384467
1.35113	1.384343
1.36714	1.384218
1.38334	1.38409
1.39973	1.383961
1.41632	1.383829
1.4331	1.383696
1.45009	1.38356
1.46727	1.383422
1.48466	1.383281
1.50225	1.383138
1.52005	1.382993
1.53807	1.382845
1.55629	1.382694
1.57474	1.38254
1.5934	1.382384
1.61228	1.382225
1.63139	1.382062
1.65072	1.381897
1.67028	1.381728
1.69007	1.381556
1.7101	1.381381
1.73037	1.381201
1.75087	1.381019
1.77162	1.380832
1.79261	1.380642
1.81386	1.380448
1.83535	1.38025
1.8571	1.380047
1.87911	1.379841
1.90138	1.37963
1.92391	1.379414
1.94671	1.379194
1.96978	1.378969
1.99312	1.378739
2.01674	1.378504
2.04064	1.378264
2.06482	1.378018
2.08929	1.377767
2.11405	1.377511
2.1391	1.377248
2.16445	1.37698
2.1901	1.376706
2.21605	1.376425
2.24231	1.376138
2.26888	1.375845
2.29577	1.375545
2.32298	1.375238
2.3505	1.374924
2.37836	1.374602
2.40654	1.374273
2.43506	1.373937
2.46392	1.373592
2.49312	1.37324
2.52266	1.372879
2.55255	1.37251
2.5828	1.372132
2.61341	1.371745
2.64438	1.371349
2.67572	1.370944
2.70742	1.370529
2.73951	1.370104
2.77197	1.369669
2.80482	1.369224
2.83806	1.368768
2.87169	1.368301
2.90572	1.367823
2.94015	1.367333
2.975	1.366832
3.01025	1.366318
3.04592	1.365792
3.08202	1.365253
3.11854	1.364702
3.1555	1.364136
3.19289	1.363557
3.23073	1.362964
3.26901	1.362357
3.30775	1.361734
3.34695	1.361096
3.38661	1.360443
3.42674	1.359773
3.46735	1.359088
3.50844	1.358385
3.55002	1.357664
3.59209	1.356926
3.63465	1.35617
3.67773	1.355395
3.72131	1.354601
3.76541	1.353787
3.81003	1.352952
3.85518	1.352097
3.90086	1.351221
3.94709	1.350322
3.99386	1.349401
4.04119	1.348457
4.08908	1.347489
4.13754	1.346496
4.18657	1.345479
4.23618	1.344436
4.28638	1.343366
4.33718	1.342269
4.38857	1.341144
4.44058	1.339991
4.4932	1.338808
4.54645	1.337595
4.60033	1.336351
4.65484	1.335074
4.71	1.333765
4.76582	1.332422
4.82229	1.331045
4.87944	1.329631
4.93726	1.328181
4.99577	1.326694
5.05497	1.325167
5.11487	1.3236
5.17549	1.321993
5.23682	1.320343
5.29888	1.31865
5.36167	1.316912
5.42521	1.315127
5.4895	1.313296
5.55455	1.311416
5.62037	1.309485
5.68698	1.307503
5.75437	1.305467
5.82256	1.303377
5.89156	1.30123
5.96138	1.299024
6.03202	1.296759
6.1035	1.294432
6.17583	1.292041
6.24902	1.289584
6.32307	1.287059
6.398	1.284464
6.47382	1.281797
6.55053	1.279056
6.62816	1.276238
6.70671	1.27334
6.78618	1.27036
6.8666	1.267295
6.94797	1.264143
7.03031	1.260901
7.11362	1.257565
7.19792	1.254132
7.28322	1.250599
7.36952	1.246963
7.45685	1.24322
7.54522	1.239366
7.63463	1.235397
7.72511	1.23131
7.81665	1.227099
7.90928	1.222761
8.00301	1.21829
8.09785	1.213681
8.19381	1.208931
8.29091	1.204032
8.38916	1.198979
8.48857	1.193766
8.58917	1.188388
8.69095	1.182836
8.79394	1.177105
8.89815	1.171187
9.0036	1.165073
9.11029	1.158756
9.21825	1.152226
9.32749	1.145475
9.43803	1.138493
9.54987	1.131269
9.66304	1.123792
9.77755	1.11605
9.89342	1.10803
10.0107	1.099719
10.1293	1.091103
10.2493	1.082166
10.3708	1.072892
10.4937	1.063262
10.618	1.053257
10.7439	1.042857
10.8712	1.032038
11	1.020778

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: —

LiF (Lithium fluoride): all datasets

Li 1976: n 0.10–11 µm n 0.1–11 µm default

About LiF (Lithium fluoride)

Lithium fluoride (LiF) is a simple ionic compound commonly used in optics and radiation detection. It is transparent over a broad spectral range, from ultraviolet to mid-infrared wavelengths. This characteristic makes it an ideal material for specialized UV and IR windows and lenses. It also serves as a mount for samples to be studied by X-ray crystallography. One of its notable features is its high resistance to radiation damage, making it useful in environments with high-energy radiation. However, it is relatively soft and is moisture-sensitive, requiring careful handling to maintain its optical properties.

More about LiF (Lithium fluoride) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/LiF/nk/Li.yml
ID: ds_3e311e71e95f
API: /v1/datasets/ds_3e311e71e95f

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