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Feit Electric Green CFL Spectrum

Feit Electric Green CFL Spectrum


This image is more of a test image to see how well i can capture the spectrum from my cheap eBay spectrum analyzer.

The reason for the green CFL is because my Feit green CFLs don't seem as green as they could be.

20200123_1923435B15D.jpg 20200123_1925465B15D.jpg 20200122_1827145B15D.jpg 20200109_0455435B15D.jpg

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Filename:20200122_1827145B15D.jpg
Album name:High Intensity / Other Photos
Keywords:Off-Topic
File Size:25 KB
Date added:Jan 22, 2020
Dimensions:350 x 254 pixels
Displayed:15 times
Date Time:2020:01:22 18:27:14
DateTime Original:2020:01:22 18:27:14
Exposure Bias:-2 EV
Exposure Time:1/17 sec
FNumber:f 2.2
Flash:No Flash
Focal length:3.701 mm
ISO:100
Make:LG Electronics
Model:LM-X210(G)
White Balance:0
URL:https://www.lighting-gallery.net/gallery/displayimage.php?pos=-171751
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Globe Collector
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Jan 24, 2020 at 07:24 PM Author: Globe Collector
That's a nice little spectrum for a first attempt. All you really need do is zoom the camera in on it to get it to fill the frame more.

This looks like a "white" CFL with green lacquer over it to block the blue and red (the "dumb" way of making a coloured CFL. A more "intelligent" way to do it would have been to omit the red and blue phosphors and possibly the green lacquer also.

Manufactured articles should be made to be used, not made to be sold!

Fee, Fye, Fow, Fum, A dead man's eye and a parrot's BUM!

High Intensity
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EYE 175w MV


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Jan 24, 2020 at 07:29 PM Author: High Intensity

This looks like a "white" CFL with green lacquer over it to block the blue and red (the "dumb" way of making a coloured CFL. A more "intelligent" way to do it would have been to omit the red and blue phosphors and possibly the green lacquer also.

That confirms a suspicion i had with the green Feit CFLs, on the other hand, it appears all of the other Feit colored CFLs use colored phosphors.

Old lighting is, and will always be, the best lighting.

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Jan 24, 2020 at 08:13 PM Author: Globe Collector
I will try to explain the spectrum, but I'm sure you will get the hang of it pretty rapidly.

It is still a little over exposed and the slit is a bit too wide. Closing up the slit will fix both issues in one go.

C.F.L.'s ("white" ones that is) have two ways of generating "white". The spectra of each look identical.

Method one they use three separate phosphors for red, blue and green and simply mix them together. They use a bit more red for 3000K lamps, a "balanced mix" for 4000K lamps and a bit more blue for 6500K lamps.


The other way involves making just the one phosphor, but controlling to doping of red, blue and green "luminophor" cations in the crystal lattice. However the spectra look the same because the same dopant ions are present, be they in one crystal lattice or in three separate lattices.


In this spectrum....on the left is the 437nm blue-violet "tittle-tat" mercury line. This line is pretty much visible in any mercury lamp unless a coloured filter blocks it. It is an atomic line coming directly from excited mercury atoms in the plasma inside the arc tube, the phosphor simply diffuses it but can't alter what it is. In the mercury atom it is produced by an electron transitioning from a higher excited state to a lower excited state...the ground state is not involved, so it isn't a resonance line.

The aqua broad band is the blue luminophor band. I think it originates from excited Terbium III ions in the phosphor crystal lattice...because these ions are trapped in a solid lattice (not relatively isolated in a diffuse plasma gas like the mercury) they are subject to the Pauli Exclusion Principle, which sort of qualitatively states that if atoms or ions are pushed close together they can't all emit the same spectral line...this is why tungsten atoms in an incandescent filament emit a broad continuum spectrum, because thay are all jammed right up against each other. In the phosphor lattice, the terbium ions are sort of in-between, not really close like in a lump of terbium metal, but not really so far apart (>few hundred atomic radii) like in a gas, so they are "permitted" to radiate all near the one wavelength...so the result is this broad band.

The next green band (overexposed) is the green luminophor band, again I think it is Terbium III in a different site in the crystal lattice...so broad, but in there too is a mercury line, the 546nm green line, as it is from the rarefied plasma it is really narrow...i.e. an atomic line.

The band that is green on the left and yellow on the right is probably another band from the phosphor, but it has the the mercury yellow doublet embedded in it too...two closely spaced atomic lines at 579 and 580nm, just 1nm apart. Resolving these is usually a goal that means you nave achieved adequate resolution for lamp spectroscopy.

The reason part of it is green and part is yellow is due to the filter set up in your camera. A different camera may blend the colour transition from green to yellow better.

The red band on the right is from Europium II luminophor ions in the red phosphor...showing that there is indeed an unnecessary red phosphor to waste efficacy in this otherwise green lamp. This band is quite dim because it is being absorbed in the green lacquer over the outside of the lamp.

Manufactured articles should be made to be used, not made to be sold!

Fee, Fye, Fow, Fum, A dead man's eye and a parrot's BUM!

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