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Quote:

Originally Posted by Ray (Post 887798)

I don't know if there are any readily available chips yet that have a phosphor "tuned" for plants, but I sure wish there were.

Some of the big players are getting close.

https://www.lumileds.com/uploads/637/DS171-pdf
Spectral distribution of their cool white (page 7) looks promising.

An interesting article, especially in regards to the author's comments about "Marketing Farf", along with his rating of 5 on a scale of 1-10.
About Seoul Semi’s New “Sunlike” LEDs | Lumenique - Inside Solid-State Lighting

Quote:

Originally Posted by wisdomseeker (Post 887807)

The above considers light from the perspective of human circadian rhythms. The discussion does not address light for plants. Plants and humans respond to very different components of light, and in very different ways.

Quote:

Originally Posted by estación seca (Post 887734)

The manufacturer may have spectrum information available that is not on the retailer's Web site.

Quote:

Originally Posted by estación seca (Post 887816)

Human Circadia Rhythms... biologocial process that is kind of like a "body clock" (tells our bodies when to sleep, wake, eat, along with other things like hormone release) - right?

SPD = Spectral power distribution of a light source. SPD graphs (associated with particular light products from various manufacturers) show the strength/power of each wavelength of light produced by a particular light source. The visible white light that the human eye sees is composed of various colors of light, usually ranging from 380nm to 760nm. I'm not a plant, but I believe they see and use these colors too.

Yes indeed, "Plants and humans respond to very different components of light, and in very different ways"... the reason some light manufacturers (e.g., the above 2 links and the particular products mentioned in those links > and please note that the SPD graphs are clearly shown in both links: pg. 7 of Phillips Luxeon "SunPlus" data sheet *the pdf file takes awhile to load*, and almost front & center of the "Semi" link) are trying to incorporate better spectrum into their products... in hopes of creating better light for plants and the human eye. Those manufacturers sure the hell are not going to share their 'secret sauce' recipes (phosphors, violet chips instead of blue chips, etc.) at how they got there, but they are getting there.

Quote:

Originally Posted by estación seca (Post 887785)

Yes. An individual Light Emitting Diode is a speck of one compound. When electricity is applied electrons orbiting the atoms in the LED are excited into a higher-level orbital. When they fall back into their normal orbital they emit a photon of light. The wavelength of light for any given compound will be the same each time this happens. An individual LED emits only one wavelength. Manufacturers combine LEDs emitting different wavelengths to make fixtures emitting white light.

In colored strings of LED lights each lamp generally emits only one wavelength of photos.

So the color of those photons of light from the electrons of the compound is managed at the primary stage of manufacturing? By the selection of the compound?

The Luxeon white is still sadly lacking in red, but a couple of those Seoul Semi chips look promising - and are available from Digi-key for DIY-ers.

There are thousands of PhDs who studied the influence of light on plant growth. Money has greatly influenced not only our life but also in the life of plants. Not everyone has the knowledge or budget. So the answer of the thread's question. There isn't one. It's what works for you, and that is different for everyone.