[Phys-L] Re: Color (was LED mini-flashlight price break)

[Bernard Cleyet <anngeorg@PACBELL.NET>]

I have taken JD up on his offer using a Flinn single beam *
spectrophotometer (lent by M. Rhodes, Chem. instructor at NS(alinas) HS.

The result w/ his much additional discussion is at:

http://www.av8n.com/imaging/dye-spectra.htm

One may there compare my rough estimate (w/ star below) and the somewhat
better Flinn.

* Don't burden you students w/ this.  Spend an addnl. $1k for a double beam.

bc


John Denker wrote:

> Bernard Cleyet wrote:
>
>
> > I've checked two food color dyes w/ my star.  The red has a very sharp
> > cut off at 600 so has a bit of orange and all the red to 700 where my
> > eye fades out.  The blue is interesting; it's only ~ 50 nm wide ~
> > centered on ~ 460 + it passes > 670, so it looks a bit purplish.  I
> > haven't bothered w/ the orange and yellow, yet.
>
> Very cool.  I would love to see spectra for the common
> FD&C colorants.  I tried googling for them with less than
> satisfactory results.
>
> If anybody can obtain the data, and send it to me, I'll
> plot it and put it up on the web.