Refractive index database

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Optical constants of NaI (Sodium iodide)
Li 1976: n 0.25–40 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]


Conditions & Spec sheet

temperature: 297 K


297 K (23.85 °C).


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 derivation is based on a single data point and knowledge of the dielectric constants and the characteristic absorption peaks.


[Expressions for n]   [CSV - comma separated]   [TXT - tab separated]   [Full database record]


Sodium iodide, NaI

Sodium iodide (NaI) is a white, crystalline solid that can be prepared as transparent crystals suitable for optical applications. Notably, when doped with thallium (NaI:Tl), it becomes a scintillator material, capable of converting incident gamma rays into visible light. This property makes NaI:Tl crystals particularly valuable in radiation detection, gamma spectroscopy, and other nuclear medicine applications. However, NaI, being an alkali halide, is hygroscopic, meaning it readily absorbs moisture from the environment. Therefore, it requires careful handling and storage to prevent degradation, especially if it is to be used in optical systems.

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