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REFERENCES: |
    R. Althoff and J. H. Hertz.
    Measurement of the optical constants of Na and K in the range of wavelength from 2.5 to 10 μ.
    <a href="https://doi.org/10.1016/0020-0891(67)90025-5"><i>Infrared Phys.</i> <b>7</b>, 11-16 (1967)</a>
DATA:
  - type: tabulated nk
    data: |
        2.25 0.41 11.6
        2.5 0.50 12.5
        3.0 0.61 14.7
        3.5 0.81 17.2
        4.0 1.02 19.4
        4.75 1.71 22.3
        7.2 3.66 32.9
        10.15 6.43 44.5