Na I line spectrum

    Caption: The spectrum for the visible band (fiducial range 0.4--0.7 μm) of neutral atomic sodium (Na, Z=11) (AKA Na I). The image looks like an actual observation, but it may be very good computer simulation.

    Many atomic spectral lines are shown, but in dim, low-dispersion spectra perhaps only 8 lines (which are all multiple unresolved lines) may be observed. These lines will be in the ranges:

      1) violet (fiducial range 0.380--0.450 μm), 2) blue (fiducial range 0.450--0.495 μm), 3) cyan (fidicial range 0.490--0.520 μm), 4) green (fiducial range 0.495--0.570 μm), 5) chartreuse (AKA yellow green, ∼ 570 μm), 6) yellow (fiducial range 0.570--0.590 μm), 7) orange (fiducial range 0.590--0.620 μm), 8) red (fiducial rang 0.620--0.740 μm).

    The brightest lines are the sodium D lines (AKA Na I doublet, 0.589592 μm, 0.588995 μm) which may be unresolved in low-dispersion spectra. This is NOT clear in the displayed image---yours truly's having trouble guessing why.??? The sodium D lines give the sodium-vapor lamp its bright yellow color.

    A Grotrian diagram for Na I with atomic spectral line wavelengths labed in nanometers (nm) is at Na I: grotrian diagram.

    Credit/Permission: © User:McZusatz, 2013 / CC BY-SA 1.0.
    Image link: Wikimedia Commons.
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