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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: |
        2.5 0.346 7.55
        3.2 0.648 9.65
        4.5 1.38 14.3
        5.5 1.66 17.1
        7.2 2.89 21.6
        10.15 4.77 28.2