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I'm just going to let these pictures that I just took speak for them self. There's no trickery going on here. It's simply making blue light from green. Even works with a 5 mW laser pointer.
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Anyone care to guess how I did this?
Upconversion via excited state absorbtion? Anyhow, very interesting!
does it come out blue or does it just look blue in the liquid?
Hey Sir Tocket...
Fluorescein? Blueberry Jello? :D Well, whatever is is, get a focusing lens and a resonator on that puppy and send us s'more pix! *retardoQuote:
Originally Posted by tocket
cheers...
j
PS - I think it's really bitchin that we have so many 'varied skills', here, within the 'PL-Family'... I think PL could make one helluva Laser Show Co. :cool: I mean, we've got it all -
EEs, MechE's, OpticalE's, Chemists, talented Machinists, Artists, Musicians, Programmers, Laserists, *real* DJs :rolleyes: and, heh, a " Janitor " who's prose is so satirically razor-sharp and visual, that he should be writing screenplays *retardo
... We even have all the 'high-drama' elements of an Office / Co. - back-biting and 'office politics' and flame wars and fights and... *retardo
...heck, we've even got a 'Dartboard / Cooler-goon!' *retardo
Long live PL! :)
cheers...
Lanthanide nanoparticles?
Nice to see some guesses. You haven't managed to solve the mystery yet though. I'll give a first hint: The blue light is in fact quite violet - The emission peak is around 410 nm, but the emission is rather broad and comes from a well known organic dye.
A bunch of excited states are involved - quite complex process. However, it does not require any double excitations, which is why it works at such low power densities.Quote:
Originally Posted by andythemechanic
It's just blue in the liquid. The absorbance of the solution is pretty low at 532 nm, so only a small part of the light is absorbed.Quote:
Originally Posted by flecom
Wish I had a resonator. Though I suspect this system would actually prefer to lase at a completely different wavelength than 410 nm. Perhaps 700 nm? Not very useful for us.Quote:
Originally Posted by dsli_jon
No lanthanides required :)Quote:
Originally Posted by Robin
Hm, is it possibly a FRET like energy transfer from serveral excited molecules to another? Do you have it published already?Quote:
Originally Posted by tocket
Greetings
Andreas
You're getting close now. There's no Förster energy transfer involved in the process though.Quote:
Originally Posted by andythemechanic
Similar systems have been published. I don't think this particular one is out yet, but it's not my publication. I'm working more towards an application of it you could say.
this thread is WAAAAAAAY beyond my pay scale! lol.
Very interesting though!
so, my answer of, "Pretty green light makes weird wet stuff turn blue-ey in color" is not an acceptable answer i gather?:p
-Marc
Time for another clue: The system is very sensitive to oxygen. If a little air gets in no blue light is generated.
Well, your answer is correct. Just not very specific. :)Quote:
Originally Posted by gottaluvlasers
Hrmm, well, I was going to submit something in the 'optical brightener'-family, common in 'brite-white' papers and detergents, or possibly, acridine yellow...till I saw the 'sensitivity to O2'... so, now I'm :confused:Quote:
Originally Posted by tocket
...Umm, Tinkerbell pee? *retardo
j
Just a guess here, could it be some kind of ET primer like the ones used in dna sequencing?
is it the stuff from a glowstick?
Don't know what is used for DNA sequencing, but are they really capable of upconversion at low intensities?Quote:
Originally Posted by DjMagnus
One of the dyes in this system can actually be found in blue glowsticks. Namely, the super-efficient fluorophore, 9,10-diphenylanthracene (DPA).Quote:
Originally Posted by Vidal Wolf
Now comes the interesting part. DPA only absorbs UV light, which is not present here. Yet, it is clearly emitting light in my little vial. Well, there must be another dye in the solution. However, the other dye will not be able to transfer its energy to DPA in a FRET-like manner, simply because green light is less energetic than blue. That would violate a bunch of laws of nature.
It's getting more and more interesting! You actually brought me to searching for literature on the effect. I found this: http://pubs.acs.org/doi/abs/10.1021/ja075014k
There the trick is to excite a red flourophore (e.g. PdOEP) which then enters it's triplet state and can transfer energy radiationless via triplet-triplet anihilation (didn't even know before that such a process exists ;) ). That also explains why oxygen hinders this process, since oxygen will lower the lifetime of the triplet state and not allow for energy transfer anymore.
Yep, triplet-triplet annihilation is the secret here! I use a different triplet dye, but the principle is the same.Quote:
Originally Posted by andythemechanic
It's quite a beautiful process. The first key step is triplet-triplet energy transfer from the excited triplet dye to the triplet acceptor, in this case DPA. The magic then happens when two DPA triplets collide and undergo triplet-triplet annihilation. In that process you end up with one DPA molecule in an excited singlet state and the other in the ground state. The excited DPA will then decay giving the blue light.
Thanks Tocket for showing this nice effect! I just realized that quite a lot of work on this topic was done in the institute where I did my PhD (MPI for Polymer Reasearch, Germany). I worked however on a completely different topic, so I had no Idea. :)
Greetings
Andreas
...thanks for the dual chem and laser-research lesson... :)
Hah, that would be a killer name for a punk-band...:) ...and 'Tinkerbells' Pee' could open for them... *retardoQuote:
Originally Posted by tocket
cheers...
j
Educational AND funny thread, very nice! :)