Optical constants

Refractive index of K (Potassium)

Whang et al. 1972: n,k 0.116–0.315 µm

Data: tabulated nk
Range: 0.116–0.315 µm
Points: 41
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 0.8926
Extinction coefficient k: 0.0546

Permittivity ε₁: 0.793754
Permittivity ε₂: 0.0974719

Absorption coefficient α: 35922.7 cm⁻¹
Penetration depth δ = λ/(2πk): 556.751 nm

Abbe number V_d: —
Chromatic dispersion dn/dλ: -2.4 µm⁻¹

Group index n_g: 1.351
Group velocity dispersion: — fs²/mm

Dispersion parameter D: — ps/(nm·km)
Photon energy: 6.49132 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

# K (Potassium): Whang et al. 1972: n,k 0.116–0.315 µm
k = ls.fetch_refractiveindex("main", "K", "Whang", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(k.range_nm)  # (116, 315) nm
eps = k.eps([191])  # 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_f2d420c078f7/lightsmith"
k = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(k.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (k/whang-1972).

# ... load k as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=k)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=116, stop_nm=315, 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.

References

U. S. Whang, E. T. Arakawa, T. A. Callcott. Optical properties of K between 4 and 10.7 eV and comparison with Na, Rb, and Cs. Phys. Rev. B 6, 2109-2118 (1972)

doi:10.1103/physrevb.6.2109 Optical Properties of K between 4 and 10.7 eV and Comparison with Na, Rb, and Cs, Physical Review B (1972)

Cite

U. S. Whang, E. T. Arakawa and T. A. Callcott. Optical Properties of K between 4 and 10.7 eV and Comparison with Na, Rb, and Cs. Physical Review B, 6, 2109-2118 (1972), doi:10.1103/physrevb.6.2109; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

41 rows as published

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

K (Potassium), Whang et al. 1972: n,k 0.116–0.315 µm: n and k versus wavelength
λ (µm)	n	k
0.116	0.945	0.027
0.12	0.945	0.031
0.125	0.945	0.037
0.13	0.945	0.042
0.135	0.945	0.048
0.14	0.945	0.052
0.145	0.943	0.056
0.15	0.941	0.06
0.155	0.939	0.061
0.16	0.935	0.062
0.165	0.931	0.061
0.17	0.926	0.06
0.175	0.921	0.059
0.18	0.915	0.057
0.185	0.906	0.056
0.19	0.895	0.055
0.195	0.883	0.053
0.2	0.87	0.052
0.205	0.855	0.05
0.21	0.842	0.049
0.215	0.826	0.048
0.22	0.81	0.046
0.225	0.794	0.045
0.23	0.776	0.044
0.235	0.758	0.044
0.24	0.74	0.043
0.245	0.72	0.043
0.25	0.7	0.043
0.255	0.68	0.043
0.26	0.66	0.043
0.265	0.637	0.044
0.27	0.61	0.046
0.275	0.58	0.048
0.28	0.55	0.05
0.285	0.52	0.053
0.29	0.485	0.057
0.295	0.45	0.061
0.3	0.412	0.067
0.305	0.375	0.073
0.31	0.335	0.082
0.315	0.303	0.095

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: —

K (Potassium): all datasets

About K (Potassium)

Potassium (K) is an alkali metal that is highly reactive, especially with water. While potassium itself is not used in optical applications due to its reactivity and lack of transparency, its compounds, like potassium bromide (KBr) and potassium chloride (KCl), are highly useful. These compounds are often used in the form of transparent crystals for the transmission of infrared light in a range of spectroscopic techniques, including infrared spectroscopy. Potassium compounds can also serve as host materials for various dopants in solid-state lasers and optical amplifiers. Potassium's reactivity and solubility often necessitate special handling and storage conditions to maintain optical quality.

More about K (Potassium) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/K/nk/Whang.yml
ID: ds_f2d420c078f7
API: /v1/datasets/ds_f2d420c078f7

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