(04 September, 2006)
Aesculin (the modern spelling is Esculin) has been known for many years. It is related to coumarins and umbelliferones. Aesculin is extracted from the bark of Horse-Chestnuts (of which the most commonly grown kind seems to be Aesculus hippocastanum) and presumably related species like the various kinds of Buckeye. Aesculin is brightly fluorescent, particularly in basic solutions; it has been lased and reported in the literature once that I’m aware of. Aesculin is a hemolytic toxin, so you shouldn’t eat any horse-chestnuts that you haven’t first crushed and soaked in several changes of boiling water.
I was able to obtain a small quantity of Aesculin Sesquihydrate, and have now lased it in superfluorescent mode, in 95% Ethanol with a small amount of ammonia. Here is a photo. The dye cuvette is on the right, its output on a paper target on the left. The “dye” was pumped by the (focused) output of a nitrogen laser I built.
I will post a tuning curve here when I have it.
I should note that I have not yet lased any extracts
that I have made myself, but I certainly hope to do so
at some point. (I have access to a small buckeye bush.)
(04 September, 2006)
Quinine has fluorescence quantum efficiency of about 0.55 in slightly acid solutions. This makes it a mediocre candidate for lasing, but in fact it has been lased. (If you want a comparison, Fluorescein has quantum efficiency of about 0.96 in slightly basic solutions.) Quinine is commonly available in the form of tonic water, which is sold in supermarkets. If you want to lase it, you will need to get the bubbles out and add some acid. (It is customary, in laboratory demonstrations, to use 0.1N sulfuric acid; I am looking into this to see whether other acids will also work.) Unfortunately, the concentration of quinine in tonic water is very low, and it is not suitable for nitrogen laser pumping. If you want to try concentrating it by evaporating some of the water, I would suggest that you use a diet tonic water, so you don’t end up with a thick syrup.
As of late 2008, quinine is also available in raw form:
It cannot be trivial to obtain laser dye from bark,
but it is certainly likely to be an interesting exercise...
(04 September, 2006)
There are two common forms of Chlorophyll in higher plants; these are called “A” and “B”. Chlorophyll A has relatively low fluorescence quantum efficiency, but has been lased. As far as I am aware, the fluorescence efficiency of Chlorophyll B is so low that it has not been lased. When chlorophylls lose their magnesium ions, they become corresponding pheophytins; Mitsuo Maeda, in his book on Laser Dyes, mentions these and the related phycocyanins. It may be possible to get some of these in reasonably pure form, and I think that some of them have better quantum efficiency than Chl A, which suggests that they worth taking a look at.
In the process of extracting chlorophyll from some
kale, I noticed that one of the layers of my extract
had a fairly bright blue fluorescence. I will be
looking into this, trying to figure out what is
responsible and whether it can be lased.
(05 September, 2006)
I have seen a report of two fluorescent substances
that were obtained from oat (Avena sativa)
roots. If memory serves, these compounds are
coumarins or umbelliferones, which would make
them related to several known laser dyes, and
to Aesculin. I will be looking into this.
(27 December, 2008)
In the course of investigating a particularly fluorescent mold that I found in my refrigerator —
— I started looking for information on the Web
about mold fluorescences. I have yet to identify the
mold, which I am attempting to culture, but I did
find a mention of Kojic Acid, which forms an intensely
fluorescent derivative when you oxidize it. I will be
attempting to look into this at some point. In the
meanwhile we will see whether I can grow more mold,
whether the fluorescent compound can be extracted,
whether it is stable in solution and, if all of those
conditions are met, whether it can be lased.
Email: a@b.com, where my first name (just three letters, no “H”) replaces the a, and “joss” replaces the b.
Phone: +1 240 604 4495.
Last modified: Sat Dec 27 10:40:25 EST 2008