Luminous aesculin and fraxin clouds (UVIVF)

[Kai]

The following experiment inspires my students again and again. A real highlight ;)
Thin branches of Fraxinus excelsior and Aesculus hippocastanum are cut lengthways and placed in water. Clouds of extracted aesculin (bluish-white) and fraxin (green-white) then fluoresce nicely, especially if you stir very slowly.

 

 

According to Wikipedia (German entry), these compounds (gucosides of coumarin derivatives) were the starting point for the development of modern optical brighteners. 

 

[dabateman]

Very interesting, 

Now if you place a white flower in the water mix, will it draw up the fluorescent molecules and show fluorescence on the petals? 

I wanted to try that with highlighter ink. But this might be less toxic and more natural to see the inner veins of the flower. 

[Andrea B.]

Lovely experiment! It is good to have this reference for those of us who like to photograph fluorescence. I love the swirls of fraxin and aesculin.

 

Have you shown your students the red fluorescence of chlorophyll under UV light? That's always cool to see too.

 

I had to look up the botanical specimens. Fraxinus excelsior is the European Ash which is in the olive family Oleaceae. Given that I don't have any Ash trees here, I wonder what one of my Russian olives might show? I must try this.

 

Aesculus hippocastanum is a Horse Chestnut tree in the soapberry family Sapindaceae. We don't have that either, but there might be something else from that family.

[Kai]

1 hour ago, dabateman said:

Very interesting, 

Now if you place a white flower in the water mix, will it draw up the fluorescent molecules and show fluorescence on the petals? 

I wanted to try that with highlighter ink. But this might be less toxic and more natural to see the inner veins of the flower. 

There are a lot of coloring processes with fluorescent dyes in microscopy. Maybe they also work on whole plants? 

[Kai]

54 minutes ago, Andrea B. said:

Lovely experiment! It is good to have this reference for those of us who like to photograph fluorescence. I love the swirls of fraxin and aesculin.

 

Have you shown your students the red fluorescence of chlorophyll under UV light? That's always cool to see too.

 

I had to look up the botanical specimens. Fraxinus excelsior is the European Ash which is in the olive family Oleaceae. Given that I don't have any Ash trees here, I wonder what one of my Russian olives might show? I must try this.

 

Aesculus hippocastanum is a Horse Chestnut tree in the soapberry family Sapindaceae. We don't have that either, but there might be something else from that family.

Thank you, Andrea.

Aesulin source: Wikipedia also names "California buckeye" (Aesculus californica). The name sounds promising...

Swirls: Yes, the dynamics of these flow and diffusion processes are aesthetically very appealing, especially in reality :)
Red chlorophyll fluorescence: Yes. Easy to show, especially with the ZWB2-filtered UV flashlight. Last year we had a student research project on the Kautsky effect. We examined the change in this fluorescence over time on different plants and parts of plants. Very interesting! 

[colinbm]

Thanks for showing these Kai, very interesting & inspiring.
I have been slowly getting a collection of UV lights together & filters in UVA, B, C & far UVC.
The next is to get some Far UVC fused silica wares to contain these samples, these seem to be scarce in Australia ?

 

[colinbm]

Kai, not knowing your set-up here, lights, filters, glass ware, etc, I am wondering if a UVA cut polycarbonate shield / window, between the subjects & the illuminated experiment, might improve the fluorescence, not just for the viewer but the camera too,  & block the exciter's wavelengths, & add some UV exposure safety ?
Then you will have the safety in place for lower wavelength exciters ?

[Kai]

10 hours ago, colinbm said:

Kai, not knowing your set-up here, lights, filters, glass ware, etc, I am wondering if a UVA cut polycarbonate shield / window, between the subjects & the illuminated experiment, might improve the fluorescence, not just for the viewer but the camera too,  & block the exciter's wavelengths, & add some UV exposure safety ?
Then you will have the safety in place for lower wavelength exciters ?

You are right, Colin. But this was a most simple setup for students. You see a single image from a film in which the luma values of various spots should be read out as a function of time. So it was about the decrease in the intensity of the fluorescence - and it worked perfectly.
Later I actually filmed through a yellow filter. Then the blue components in the film fall away. But nothing changes in the rates of change.