WATCH: Sugar in liquid nitrogen glows when exposed to UV light


Time to play – I need to remember to bring my cat pee flashlight to work tomorrow…


Many organic things do fluorescence under UV. (Hence the cat pee effect.) It can be a real bitch with Raman spectrometry, as it forces use of red or near-IR (sometimes you can get away with green), and high power that thermally loads the sample, instead of lower-power blue/violet laser, if you don’t want the fluorescence signals all over the place.

I guess sugar fluoresces under UV even at normal temperature (likely much weaker?), but the cooling allows for longer retention of the excited states, suppresses the nonradiative deexcitations, and generally makes it shinier?

Couldn’t find a fluorescence spectrum of sucrose. Internet is mean to me.
Consolation prize: here, triboluminiscence spectrum of sucrose and some more.


I had never really thought of the temperature effect on quantum nature that is more easily believed in a luminescent watch paint where the sticky quantum states collapse over several hours. This effect is why we need a good heat sink on high power white LEDs or you are just wasting more power for more heat but which reduces actual light output. The blue or UV LED pumps a white florescent coating, efficiency is getting better but you still see see bright LEDs start bright but then drop after ~.2 sec as they warm up.


Would a Peltier cooler help enough to justify its cost and power consumption?

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A few years ago I spent some time reading from the LED geeks on
I seem to remember that being a topic but I don’t think many people adopted it, I was concerned with portable use and battery life, what I learned from the state of the art then was that a good heat sink into an aluminium body held by a human hand keeps the LEDs at a reasonable temp.


Sugar goes in liquid nitrogen, sugar glows when exposed to UV light.

You can’t explain that.

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