RE: [APD] If it's good for street light...

["Nestor D. Groel" <nestor_groel at lorien-sistemas_com>]

Hi Mariano:    

The fact that you explain it´s true ONLY if one photon it´s emitted from one orbit. In quantic terms (i.e. statistical terms
involved there) all quantified energy level are possible but the potential, material and doped of the junction (bandgap), limits the
statistical possible window. Not only one wavelength it´s emitted from a LED, it´s a range of statistical permited wavelengths.

A monochromatic led it´s the purest example, where the spectral emition it´s centered in the statistical maximum, but a lot of
others wavelenght are emitted in agreement of the statistical window permited to the physical characteristics of the junction. While
the possible energy levels of each photon it´s quantified (i.e. their wavelength it´s quantified), all of photons emitted can have a
wavelength determined by the gauss distribution curve and the emittion spectra of a LED it´s seen like a continuos distribution of
all wavelengths in the permited range.

In the "white" LED two models are developed. One that put three junction, Red Green Blue in the same package and with certain
balance and the resulting emitted light it´s seen by our eyes as "white" light. The other methods uses the phosphor fluorescence
(like in the fluorescent lamp) exited by a deep blue or UV LED. In some cases a mix of two models are used to produce a better
spectra. 

Cheers

Néstor D. Groel
PM: Sorry for my bad english

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> -----Mensaje original-----
> De: 
> aquatic-plants-bounces+nestor_groel=lorien-sistemas_com at actwin
.com [mailto:aquatic-plants-bounces+nestor_groel=lorien-> sistemas_com at actwin.com] En nombre de Mariano F. Bonfante
> Enviado el: Lunes, 18 de Julio de 2005 11:42 p.m.
> Para: aquatic-plants at actwin_com
> Asunto: Re: [APD] If it's good for street light...
> 
> Nice site Scott. Let me ask you about the white leds. I study 
> years ago that the light emission of a PN junction was 
> related to an electrode coming down from an excited orbit to 
> a more stable one. In this case the photon released has a 
> specific wavelength related to the orbit energy difference.
> 
> In this aspect, a white emission would not be possible.
> 
> Other way to produce such spectrum is to operate a light 
> emitter with extremely narrow pulses, so the emitted light 
> would be white.
> 
> Do you have an idea how white leds work?.
> 
> Mariano
> 
> 


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