[Rockhounds] colour perception, organic fluorescence, etc

Sun Dec 14 09:32:47 PST 2008

Hi Jim,

Those glow-sticks are a quite different process.
It's called chemoluminescence. You have two solutions, one of which is a
oxidant. 
Mixing the fluids starts a slow oxidation. The rearrangement of chemical
groups causes the light-emission. 
There are two basic processes: chemical and biochemical.
You can easily do the chemical one as follows (be careful: KOH is dangerous
for skin and eyes):
Make solutions in water of 15% potassium hydroxide, 15% pyrogallol (1,2,3
trihydroxybenzene) and 10% hydrogen peroxide. 
Mix the solutions in equal amounts (SMALL amounts of a few CC at a time).
You should see a red glow or at least a red flash. It works even better when
you do this in the dark ;-))))) LOL

The bioluminescence in fireflies is caused by luciferol , a complex organic
molecule, which is attacked by the enzyme luciferase. Both are made by the
firefly's metabolism.
The luciferol reacts with oxygen to form an instable dioxytanone. In turn,
this chemical substance decays to CO2 , adenosine monophosphate and a
quantum of light.

Cheerz

Axel Emmermann
European Regional Vice President of the
Fluorescent Mineral Society
<http://www.uvminerals.org/>
=========================
Mineralogische Kring Antwerpen/Antwerp Mineralogical Society
<http://www.minerant.org/index.html>
Werkgroepleider/Workgroup leader: Fluorescerende mineralen/Fluorescent
minerals
Technische Realisaties/Engineering
My website:<http://users.pandora.be/axel.emmerman/home/>

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com]
> Namens Jim Daly
> Verzonden: zondag 14 december 2008 17:29
> Aan: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
> Onderwerp: RE: [Rockhounds] colour perception, organic fluorescence, etc
> 
> Hi Axel,
> I Hadn't read this before my last reply. This could be the explanation for
the foxfire
> mechanism. Might also have been helpful to the American Cyanamid people,
(if Cyanamid still
> existed)
> Jim
> 
> --- On Sat, 12/13/08, Axel Emmermann <axel.emmermann at pandora.be> wrote:
> 
> From: Axel Emmermann <axel.emmermann at pandora.be>
> Subject: RE: [Rockhounds] colour perception, organic fluorescence, etc
> To: "'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'"
> <rockhounds at lists.drizzle.com>
> Date: Saturday, December 13, 2008, 12:06 PM
> 
> Hi Alan,
> 
> I know of one mechanisme that makes some organic compouds fluoresce;
> It happens when energy is transferred between chemical groups that are
part
> of a molecule.
> If my memory serves me, rhodamine B is a good example (it used to be a
> reagent to demonstrate antimony, it gives a violet precipitate).
> Complex organic molecules vibrate (all molecules do). They can rotate,
> vibrate and stuff. Some of these chemical groups of the rhodamine B
molecule
> exchange energy each time the "flexing" molecule brings these groups
> close
> together. So the electron that carries the energy just "walks" over
> whenever
> the gap is small. Hence, no fluorescence.
> When you put it in the freezer, however, you drain some of the
motion-energy
> of the molecules, making them "less flexible". Now the electron has
> to JUMP
> the space and the rhodamine B becomes fluorescent.
> It's called cryoluminescence.
> 
> Cheers
> 
> Axel
> 
> > -----Oorspronkelijk bericht-----
> > Van: rockhounds-bounces at lists.drizzle.com
> [mailto:rockhounds-bounces at lists.drizzle.com]
> > Namens Alan Goldstein
> > Verzonden: zaterdag 13 december 2008 5:22
> > Aan: jr50wv at yahoo.com; Rockhounds at drizzle.com: A mailing list for rock
and
> gem collectors
> > Onderwerp: Re: [Rockhounds] colour perception, organic fluorescence, etc
> >
> > I also noticed a difference in color between eyes. The sky was a
different
> > shade of blue between the left and right eye (slight but noticable).
> Haven't
> > looked for the difference in years, need to try it again. As a long time
> > amateur astronomer I always had fun comparing the subtle colors of stars
> and
> > nebulae between different observers.
> >
> > I also noticed the skyglow at night was different. If I observed with a
> red
> > light, the night sky had a green color. If I looked with purple (from a
> bug
> > light), the night sky had a deep red hue. Fun stuff! My observing
buddies
> > noticed the effect, so it wasn't just me. I was the one to point it
> out.
> >
> > Poison sumac is a northern plant, not western. It is widespread in
> northern
> > Indiana. Poison oak is the western plant.
> >
> > Alan
> >
> > ----- Original Message -----
> > From: "J. R. Hodel" <jr50wv at yahoo.com>
> > To: <rockhounds at lists.drizzle.com>
> > Sent: Friday, December 12, 2008 9:11 PM
> > Subject: [Rockhounds] colour perception, organic fluorescence, etc
> >
> >
> > HI Axel, Kitty, et al:
> >
> > Someone remarked about color perception, and this not only varies
between
> > people but between eyes. Now I'll date myself . . . Back in the day
> when I
> > spent a lot of time in a darkroom and comparing color results from film
> > batch to batch, and from video camera to video camera despite the best
job
> > the color engineers could do, I noticed that my eyes had slightly
> different
> > color responses. Partly this was noticable because back then you aimed a
> > film camera with one eye at the viewfinder.
> >
> > One eye was closer to Ektachrome and one was closer to Kodachrome - go
> > figure. It's less noticable now, but still there. So comparing colors
> of
> > phosphorescence and fluorescence with the naked eye and discussing it
via
> > email may be futile. Surely the color business has sensors that make
this
> > all objective nowadays?
> >
> > Axel, here in the North American forests we have several woods that
> > fluoresce under the right stimulation. Locust (I think the black locust
> > variety native to the WV forest) glows, as does the shrub sumac. This
> isn't
> > the poison sumac which I think is a western shrub, this is a shrub which
> > bears bright red fruit clusters with which you can make a pleasent
> > non-intoxicating beverage. It glows best in long-wave "black
> light". I
> don't
> > remember which spectrum locust responds to best.
> >
> > Do we know what mechanism might cause the fluorescent reaction in
organic
> > materials?
> >
> > Just wondering, sorry if we're off topic, but it is related to black
> light,
> > etc.
> >
> > Merry Christmas, everyone!
> >
> > JR
> >
> >
> >
> >
> >
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