Chlorophyll fluorescence

[Vicki C]

I recently dried some borage leaves and immersed them in an olive oil bath, and then strained the oil. I was impressed with how bright the green was, and was taking some photos of it, trying to catch it in the light. I noticed that it was reflecting some red, and I remembered (vaguely) that chlorophyll will fluoresce when isolated from the plant - it can’t pass on energy to other molecules so it gives it off as light. (I think that’s right, but feel free to expound/correct my explanation.) I have tried this with my kids years ago but it wasn’t all that impressive.
The borage extraction however was reflecting red right away. When I took it into a closet and shined a flashlight it was really bright red.
Fun with science.

Chlorophyll extraction inside.


Chlorophyll extraction outside. You can see that the top part is reflecting red.


Chlorophyll extraction inside with a flashlight shining on it. Look how it reflects red but the light that shines through it casts a green shadow. So cool!
ETA I guess it’s not really reflecting per se - it is giving off red light.

 

[AliOop]

Not sure how I missed this post earlier, but that is really cool! Will the red show in the soap, as well?

 

[ResolvableOwl]

Thanks @AliOop, I had missed it too.

Yes, @Vicki C , that explanation is good. Actually, chlorophyll is doing here what it is intended to do in plants too: scavenge light, and convert it into other energy (we're seeing the part that becomes red light, but another part is converted into heat, and some part also destroys chlorophyll molecules, that's why chlorophyll-green things bleach over time…); but with the rest of the biochemical apparatus not present, nothing is used to build up sugar, of course. On top of this, chlorophyll is great in reflecting red/infrared light: Category:Trees in infrared - Wikimedia Commons

It is a fun experiment, and most impressive if you happen to have a green laser pointer – it will turn red inside the oil! The interwebz holds some urban myths that this can be used to distinguish true EVOO from faked (dyed). But this only works so long as the added dye itself isn't chlorophyll. Forging EVOO is as easy as infusing borage – or buying a bottle of pumpkin seed oil.

Will the red show in the soap, as well?

Well, kind of. Chlorophyll already is a tricky colourant for green soap. To make it worse, fluorescence is heavily dependent on pH and environment (oil phase/water, clear vs. scattering…). My impression is that, at least for pumpkin seed oil, the red colour wins, and the soap looks more like red grape juice, with little to none green remaining. Worst case is that some of both tints survives, and you end up with a lovely brown colour.

 

[AliOop]

Well, kind of. Chlorophyll already is a tricky colourant for green soap. To make it worse, fluorescence is heavily dependent on pH and environment (oil phase/water, clear vs. scattering…). My impression is that, at least for pumpkin seed oil, the red colour wins, and the soap looks more like red grape juice, with little to none green remaining. Worst case is that some of both tints survives, and you end up with a lovely brown colour.

Very cool, thanks!

 

[Vicki C]

Thank you @ResolvableOwl! Sorry for my late replay, I am terrible about keeping track of threads I start.
Incidentally, my daughter is an oceanographer specializing in ocean optics (yup, that’s a thing…) and gave me some info about chlorophyll fluorescence via late night text chat after I posted this:
“chlorophyll fluorometers are actually on moorings and autonomous floats all over the ocean collecting data all the time”…”they measure the solar-induced chlorophyll fluorescence from satellite even, for land plants at least. for the ocean they aim a laser at the ocean and excite the fluorescence and measure it that way!”…”when we measure the reflected light spectrum in the ocean we see a little peak in the red from the chlorophyll fluorescing, even though the water looks blue (the red light being reflected out is much less photons that the other light being reflected out)”

ETA here’s my wonderful daughter ❤ Ali Chase, PhD

 

[ResolvableOwl]

In this case, I feel the usage of the emoji exceptionally appropriate!



ETA: Addition to the chlorophyll vs. lye/soap topic: these are the soaps with 44% pumpkin seed oil, unmoulded after three patiently long days … not a bad colour, but still disappointing when compared to the pure oil, that looks like the infused oil of @Vicki C above, just 10 times stronger.

No idea how much of this colour is due to fluorescence, or mere chemical breakdown of chlorophyll into brown stuff. But lol, I guess you can tell which moulds the soaps have been in … let's see if I get this clean ever again.

 

[Vicki C]

Very nice! Is it possible that the orange / brown is from carotenoids, rather than chlorophyll fluorescence?

 

[ResolvableOwl]

Probably. I don't know how much carotenoids are in pumpkin seed oil and if they matter colour-wise. But pure chlorophyll oil (like neutral oil infused with green plants) staying green in CP soap is a thing. I genuinely don't know. It's also a bit soda ash/stearic spots/fading involved (?) since straight after CPOPing they had appeard nearly as dark as chocolate.

 

[Vicki C]

I got this gorgeous green with 40% of the borage infused OO - haven’t checked it recently but I will.
First photo after the pour, second photo the next day.