fluorescent cognac

February 16, 2009 at 1:45 pm | | nerd, science@home

I was watching bad TV the other day, and I got bored and started playing with a cool LED pen Thorlabs gave me. I was also drinking some VS (the cheap stuff) Courvoisier cognac. I was surprised to see fluorescence coming from the cognac when illuminated with the blue LED (the fluorescence is the greenish glow):


I suppose that it shouldn’t be surprising, given that cognac is so aromatic! But a visible absorption and green fluorescence isn’t from benzene or something—it’s from a real fluorophore. Cool.


So I wonder what fluorophore is in cognac. I know that coumarin (general structure above) is found in some plants, such as cinnamon, and some coumarins absorb in the blue. And there are a lot of tannins in wooden barrels.


I found these fluorescence spectra of brandy (B), whisky (W), slivovice (S), and juniper spirit (J). Note that the brandy—cognac is a brandy—does fluoresce in the blue/green.


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  1. wait, how big was that cognac glass?

    fluorescence is another great reason why i love tonic water.

    also because it tastes so good with gin mixed in it.

    Comment by joel — February 16, 2009 #

  2. i don’t have a cognac glass.

    Comment by sam — February 16, 2009 #

  3. so what was that photo taken of? a beaker? a bottle? it seems very large, that’s all.

    Comment by joel — February 16, 2009 #

  4. oh. it’s not that big. you can see my thumb in the top part of the photo. it’s just a regular tumbler—maybe called a “low-ball”?

    Comment by sam — February 16, 2009 #

  5. Couldn’t find a more obscure journal?

    Comment by mitch — February 17, 2009 #

  6. If anyone should be studying the chemistry of booze, it’s the people from Eastern Europe.

    Comment by excimer — February 17, 2009 #

  7. They left out the vodka adulterated with methanol.

    Comment by lol — February 18, 2009 #

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    Pingback by Everyday Scientist » laser pointer and a fluorescent lanyard — January 8, 2013 #

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