NurdRage - 2012-12-24
In this video we explore the colorful science of fluorescence. A really cool way to play with fluorescence at home is get a blue or violet laser pointer and shine it into a dish or jar of water where you have added a drop of fluorescent highlighter fluid. You'll clearly see the beam as the solution fluoresces in its path. Now the common definition of fluorescent is something that glows a visible color when exposed to ultraviolet light. Fluorescence is actually much broader than that and you don't need ultraviolet light in particular. For example in the yellow fluorescent dye "rubrene" both violet and green lasers will activate it and glow yellow. This proves you don't always need ultraviolet light. But a red laser will not activate a yellow dye. Why is that? What's happening in fluorescence is that the incoming light raises the energy of the electrons in the molecule to an excited state. The electrons then lose a bit of energy due to vibrations of the molecules. And finally the electrons return to the ground state by releasing light. Now since energy cannot be created or destroyed and a bit of energy was already lost as heat in the vibrations of the molecules, the energy of light emitted must have lower energy than the light absorbed. So since the yellow fluorescent dye emits yellow light, we need to use light of higher energy like violet and green for it to glow. Red is lower energy than yellow light so it can't excite the dye. It also won't work if you use the same color as the dye like a green laser onto a green dye. This is because you almost always lose a bit of energy and therefore it has to emit a different color or none at all. Another restriction is that the dye has to also absorb the light to work. For example Europium Tetrakis (Dibenzoylmethide)Triethylammonium will glow bright orange under violet light. But under green light it doesn't glow at all. This is because the substance simply doesn't absorb green light and so it can't reach an excited state where it can fluoresce. So you need both absorption and higher energy to get fluorescence. Higher energy does not automatically imply absorption. A really cool trick with absorbance and fluorescence is to get multiple fluorescent dyes of differing colors and shining various wavelengths of light on them. If you start with short, high energy, wavelengths of light you will see all the dyes glow. But as you go to longer wavelengths of lower energy the high-energy dyes will go clear as they can no longer absorb or emit light. When you reach red light all the dyes may look "clear" even though you know they are actually multiple vivid colors in white light. Now what happens if you mix fluorescent dyes? The results depend on the concentration, absorption and emission profile of the dyes. Sometimes the colors of the resulting fluorescence will simply add up and you get a mix of color. Other times the emission of the higher energy dye will get absorbed by the lower energy dye and the color you get at the end is exclusively the lower energy dye. Moving on to a new topic now: I said fluorescence worked by first using light to push electrons into high-energy states. Well if we could just push these electrons into their higher energy levels then we don't necessarily need the light. We can do this in a glow stick. A glow stick reaction uses chemicals instead of light to excite the electrons in a fluorescent dye. Now instead of using chemicals to excite those electrons we can also use direct mechanical grinding. A special range of compounds has this property called triboluminescence. On a different note: Remember when i said way back that after an electron is excited it loses a bit of energy due to molecular vibrations? It follows that if we can alter or stop these vibrations then we can change the energy of fluorescence and thus its color. A special dye called pyridine copper iodide exhibits a property called fluorescence thermochromism. It changes fluorescent color with temperature. At room temperature the color is yellow but under liquid nitrogen it changes to blue. Finally a life saving application of fluorescence is in medical diagnostics. A dye is specially engineered to glow when it comes into contact with a pathogen. Since pathogens usually only occur in tiny invisible concentrations by using one of these special fluorescence dyes a sample to be tested quickly and accurately for the presence of such pathogens. The key point is that fluorescence can still be very bright even at these tiny concentrations. So there you have it, a cool effect that helps us to understand light, have fun and save lives.
Will you tell me what dye is used to detect e-coli? Thanks in advance!
I love how he says Europium Tetrakis Dibenzoylmethide Triethylammonium like it's no problem to say.
"do not look into laser with remaining good eye" definitely a good old laser joke.
You can inject this into your veins right
no
So it's heavily implied that you can look into laser IF you have TWO good eyes.
Well, the consequences will not even nearly be as bad as if you do it with just one good eye :)
This is one of the coolest videos I've seen in a while. I really appreciate that you explained luminescence mechanism the proper way with energy diagrams without dumbifying it.
most of the dyes i bought from sigma aldrich or alfa aesar. Most of the video used: 9,10-diphenylanthracene 9.10-bis(phenylethynyl)anthracene rubrene rhodamine B tetraphenyl porphyrin and the special dye at 8:00 is a type of FRET based molecular beacon coded to the DNA of e.coli. you can buy the kit online but the compound itself is propriety so even I don't know what it actually is.
Automotive Technicians also use fluorescent dyes to detect coolant leaks. A small amount of dye in a radiator and a UV light lets you see where coolant is coming from. It's a handy tool to have.
I think this is a great video; just showed it to a group of first-year university students in a bioanalysis course after teaching the principles of fluorescence spectroscopy.
The Jablonski diagram is used in many areas of physics and chemistry.
I love your videos but this one was something special! Keep up the awesome work!
i am so glad this channel is somehow still going. i used to watch so much of it as a kid and was looking for this video specifically because it always amazes me and is a great demonstration. thank you nurdrage for helping people see the cool side of chemistry and make them want to learn! i'm more into computer science now but chemistry will always be fascinating to me.
Too be honest i don't know. Most amateurs i find get their equipment from ebay. I get mine from professional distributors like VWR. I also get glassware from chemglass. But to be really honest chemistry as a hobby is NOT cheap. Glassware is expensive and breaks easily and often. Chemicals get used up. And mistakes, even if you're unhurt, are a costly loss of chemicals. My "make luminol" video cost $2000 to make over the course of a year due to costly "exploration" of the science.
I love these so much! I wish I could pay you to make them more frequently!
I love your videos. This one takes the cake! I love the lecture/demonstration style you used here!
Thanks, cool video and informative. I was watching some of your other videos (just finished the one on glow sticks) and was wondering if some form of lamp could be made without the addition of TCPO and hydrogen peroxide by substituting the chemical energy source with another form of energy so I decided to look up how fluorescence worked and stumbled into another one of your videos lol! I guess this is how fluorescent lighting works, the glass must be coated with fluorescent material and the tube filled with some sort of gas (since I see no liquid when they break) that emits UV light when excited by electricity. I was hoping we might be able to use a non visible form of energy like infared or radio waves but I guess not since those are lower in terms of energy level than visible light... shux. I suppose from a purely academic standpoint if might be possible to make similar substances that emit a spectrum lower than the visible light spectrum... but who care about those? They don't look cool!
I guess no one wants a radioactive lamp...
Anyhow, very informative, always fun to learn, thanks a bunch.
Wow, this was so interesting! Thank you for uploading this - very nicely edited and I'm living that new intro! Keep it up!
I always like your videos, but this one was particularly informative! I learned a lot!
This was probably one of my favorite videos :) Great presentation, fascinating topic. I've been subbed for a long time, and check back constantly to watch your videos.
Loved learning about this! Thanks for the education
Please upload more often, this was really interesting :)
Even though I am a Bio major, I love going into chem. its sooo cool. Thanks for all of your investments for our enjoyment :)
This would be such a great video to watch before designing a lighting system for a game! I'm keeping this one around for future reference :)
Thanks for the advice! I'm going to try to pick up pieces one at a time whenever I have money, eventually I'll have enough!
This an amazing video! Very well thought out, Taught me much more then chemistry class did on the topic.
That was a *very* educational video. I love it, great stuff! :)
This vid deserves so many more views. Presented in an interesting, clear and precise manner, defiantly worth a sub :D
Man that was freaking awesome. Thanks for sharing. I believe that you need to learn something new every day and you did it for me.
@NurdRage- I love it! Too Cool! Do you know where I can find paint or paint additives that allow for florescence? Is there anywhere that shows adsorption/emission correspondence organized by additive (or compound)? Thank you!
omg thank you thank you! im really interested in the interaction between matter and light, this video helped soooooo much!!!! :-)
This is incredibly fascinating, thank you very much!
This probably is my favorite clip you ever made. Very interesting!
I love how you tied in every other video you made regarding fluorescence. Excellent video :)
thank you nurd, I used to love physics more now chemistry is one of my favorite sciences
@WoundedSnake wtf, this is a seven hears old comment. I thought you must have dead.
*years
@Knitz yes, I should be dead, because humans can NOT live longer than 7 years!!!! btw your grammar sucks ass
I feel sorry for you and really hope English is not your first language
@WoundedSnake 😂
sorry for give u a bad mood. That's so freaking funny for me, I don't know why.
I started watching with 1 video now im hooked :o amazing stuff makes me want to learn more science!
I very much enjoyed this video. It really helped me to understand the various other fluorescence videos you have on a better level
Another phenomenal video loved it!
This video was PERFECT! I only wish you uploaded more often
You're so cool! Thanks for teaching me in such a fun way that was very digestible!! Amazing video!!
Amazing, thanks for the upload! Merry Chemistrymas!
Added to my short list of favorite videos, THANKS FOR THIS!
Nurdrage, I love your videos and because of them and my great teachers, I'm going to major in chemistry in college. Every time I see a concept in your videos that I've learned about, it just seems so cool. This might have been asked before, but where did you go to college? Chemistry is awesome!
Videos that explain the theory behind the awesomeness are my favorite kind.
This is awesome. I recently learnd about fluorescence in physics, but the chemical aspect and its usage is just as impressive.
This is one kick ass video, spectacular job! Thank you!
NR, this is a phenomenal overview of fluorescence. As a fellow chemistry teacher, I salute you! :-)
This was amazing. I just had a little epiphany about fluorescence... Now to go make some simulations :) You should do some of these informative videos more often! You're great at them.
wow thank you for this. ive always had an interest in flourescence but never really got into how it works. you made everything easy to understand. nice job.
Thank you Mr. Rage (or is it Dr. Rage?). I love your videos. You make me feel like I'm sitting back in science class. I hope to see many more videos from you in the future.
This was best educational chemistry video I ever saw :D I understood many things that didn't got in normal school lessons Thank you NurdRage! Looking forward for more awesome video lessons like this one c:
Smash Glow Crystals is still the coolest vid I've seen. Still though, light has always been the most interesting subject in physics.
TKOR - 2012-12-28
Thanks. Yes I would like to give it a try. Any more information you can send is helpful. Thanks again!