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graphics - How to plot an emission spectrum?


If I have a list of data with various wavelengths in nanometers, how would I plot them on a graph so it looks like this: emission spectrum


So far I have managed to plot a spectrum in DensityPlot, but I have no idea how to hide values that are not in my data set. I do not know if this is the correct method.


DensityPlot[x, {x, 300, 800}, {y, 0, 1}, 
ColorFunction -> ColorData["VisibleSpectrum"], 
ColorFunctionScaling -> False, AspectRatio -> .3]

I should also note that my data is nonintegral.



Answer




You can also construct the image from Graphics primitives, which ultimately may give you more control:


spectrum[list_List] :=
 Graphics[
  {Thickness[0.005], ColorData["VisibleSpectrum"][#], Line[{{#, 0}, {#, 1}}]} & /@ list,
  PlotRange -> {{380, 750}, {0, 1}}, PlotRangePadding -> None, ImagePadding -> All,
  AspectRatio -> 1/5, ImageSize -> Large,
  Axes -> None, Frame -> {True, False, False, False},
  Prolog -> Rectangle[{0, 0}, {1000, 1}]
  ]


Using this helper function, we can plot the principal emission lines of a neon lamp (data):


Ne = {448.809226, 533.07775, 540.05617, 565.65664, 576.44188, 
   580.44496, 585.24878, 588.1895, 594.48342, 609.61631, 612.84499, 
   626.6495, 633.44278, 638.29917, 640.2246, 650.65281, 667.82764, 
   703.24131, 724.51666, 743.8899, 748.88712};

spectrum[Ne]

Mathematica graphics




Thanks to J. M. who pointed me towards an improved, more faithful version of the "VisibleSpectrum" color function developed by Mr. Wizard (A better “VisibleSpectrum” function?), whose code I reproduce below:


(* needed to pre-load internal definitions *)
ChromaticityPlot;

(* Mr. Wizard's Visible Spectrum color function*)
newVisibleSpectrum = With[
   {colors = {Image`ColorOperationsDump`$wavelengths, 
       XYZColor @@@ Image`ColorOperationsDump`tris}\[Transpose]},
   Blend[colors, #] &
   ];


This new color function can be included in a modified spectrumNew function:


spectrumNew[list_List] := 
 Graphics[{Thickness[0.003], newVisibleSpectrum[#], Line[{{#, 0}, {#, 1}}]} & /@ list, 
  PlotRange -> {{380, 750}, {0, 1}}, PlotRangePadding -> None, 
  ImagePadding -> All, AspectRatio -> 1/5, ImageSize -> Large, 
  Axes -> None, Frame -> {True, False, False, False}, 
  Prolog -> Rectangle[{0, 0}, {1000, 1}]
 ]


corrected spectrum


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