 And with that I'm happy to present Mitch Anstey who is also from Sandia National Labs Hi, everyone. My name is Mitch. I am as Rick said a scientist at Sandia National Labs I got my PhD in chemistry at Berkeley doing basically nothing like what I'm going to talk about here today Pretty much everything I'm going to talk about is something I've learned in The past week or it's actually something that I learned Over the past three years of working at Sandia where I've really tried to expand and learn something new and very cool and so This new this job has actually allowed me to do that which I'm good look to all you but in graduate students out there It's tough so My talk is about luminescence in all the different ways that We can make light with different compounds But so luminescence is you know the definition is Emission of light from a material and atom a molecule Upon some stimulus you you have to put energy in to get energy out. That's really how how everything works But the one stipulation with luminescence is that it can't be heat. It can be just about anything else. It can be I Mean it can be another photon of light to then give energy to a Compound and then you get that photon right back out. Maybe at a different wavelength You can do electricity. You can use radiation So that's part of what we do at Sandia using luminescent compounds to let us know whether there's a dangerous nuclear weapon nearby or a dangerous chemical or biological weapon nearby So that's what myself and and a couple other people in the audience actually do But so even living organisms and you've probably seen tons of those examples So, you know, I think I've already said the slide But it's the idea is energy in and energy out just not heat as that energy in You start off with some compound a you know a represents an atom it can represent a big solid It can represent an LED LED light bulb but you put you Give energy to it and then it goes into this excited state So it's now itself plus that extra little bit of energy that you've given it What you've done in this instance though is Given that compound some extra energy in its electronics in the electronic state So electronic I'm actually talking about electrons electrons protons neutrons and that This electron is now further away from its positive charge Obviously positive and negative they attract one another they want to be closer and so it finds a way to then Give that energy back to pull that negative charge right back towards wherever that positive charge happens to be and Eject another photon of light So this can be a photon this can be you know Mechanical force it can be some chemical reaction, but in the end You move this you move electrons around and you get your light right back out. So Again incandescence is heat so team incandescent. They've got some pretty cool people on their squad They've got molten lava. Okay big deal They've got they've got fire I mean, but like an incandescent light bulb nobody even uses those anymore But the Sun, okay, give her of all life got to give some props to that but on team luminescence We've got black lights way better than incandescent Like these are selling like all over the place in Colorado in Oregon right now Everybody's got to have a black light We've got lasers we can do laser light shows they can't do that Where they have the Sun? We have cyclops that is bioluminescence to the max I mean this a guy shoots lasers out of his eyes That is the epitome of luminescence and bioluminescence and forget avatar. I will always go go for Cyclops So Back to luminescence You know everyone wants to be an expert in a field And sometimes it's really hard to be an expert in a really big field. So we kind of chop it up You know like it's kind of hard to be into all alcohol So now you've got to be like I'm a mixologist or like oh, I'm really into Vinology or I brew my own beer now So it kind of happens with So I kind of happens with luminescence to that that people have differentiated this entire field of luminescence by All the inputs. What are what are these energy inputs that you can do? So a lot of the names are pretty self-explanatory. You've got mechanical luminescence for mechanical work mechanical force You've got a bioluminescence for biological organisms radio luminescence for radiological Sorry for radiation And so because there are so many I can't really talk about I intended to and then I started making the talk and I realized I only have 15 minutes. So I concentrated in the ones that I thought were Really cool to demonstrate to you guys. Obviously. I'm not gonna do radiation here So what I decided to do so I I know I'm sorry Sorry, we all want to be a cyclops, but it can't happen that quickly. Some have to die So Well, that was not a planned joke that was like all ad lib Um So I'm gonna talk about I'm gonna show photo luminescence. I'm gonna show McKenna luminescence, and I'm gonna show chemi luminescence right at the end so photo luminescence you see this all the time every single day of your lives every time you look at a piece of white fabric you Look at a piece of paper notebook paper any sort of white paper Even cosmetics that these compounds are in Cosmetics basically so again photo luminescence is light in is absorbed into the electronic state of a compound and then it's re it's emitted again With a slight change in the wavelength based on some energy loss to do these electronic transitions so So a lot of the compounds that you'll find these fluorescent compounds and laundry detergent paper whatever They'll convert this invisible UV light the light that is just outside the visible spectrum and They'll convert it into blue light light that we can see Essentially giving an optical illusion that all of a sudden it's glowing you don't The light that is being put around Doesn't add up for your eyes as to what is coming out back at you and so And in addition to that blue light is best for this because in a lot of these these are natural These are natural fibers you can only bleach things but so much before they're just not useful for their intended purpose So you counteract you balance that little bit of yellow with a little bit of blue to make it perfectly bright white so Let's see Yeah, so let me see so in and going back to cosmetics So you'll see a lot of fluorescent compounds like this in cosmetics in compounds or sorry in cosmetics that hide age spots or dark lines or shadowy eyes or you know, I don't know those sorts of things because What it actually does is it takes that UV light Especially if you're outside takes that UV light that hits these spaces like maybe under your eyes or or a dark area And I'll actually make it glow all of a sudden So it's really just a an aesthetic thing, but it's chemistry and photo luminescence working in your favor. I suppose So again Electromagnetic magnetic spectrum Just outside the visible and emits it back in the blue making it appears if it's going to glow so um Now here is a picture of one molecule brightener 28. It's common in detergents and t-shirts That's why you know when when me and my rage crew were hanging out These guys like you know all of all of a sudden our shirts are glowing blue But but also um, so it's in sunscreen as well So sunscreen, you know the best way to protect your skin from UV light is to is to put a layer of compound That absorbs the UV light so it actually Gets in between that UV light in your skin. So it doesn't damage your DNA or or give you a sunburn and also in It's a quinine is a compound in tonic water, but It's not there because it's fluorescent. That's not the intended purpose. Although it is a very cool effect This actually just has medicinal purposes and happens to be fluorescent. So actually Rick if you could come and Actually bring a gin and tonic for us because I have to say I'm awfully thirsty all of a sudden And so if I just put this black light right here and Like that much Let's good for you because I didn't pay for it. So well first off But then also you can see No, you can kind of see it, but let's do it. So that doesn't work so well But so here's just a bottle of quinine that I purchased, you know from Safeway, whatever And so this is really, you know, you would say that that looks colorless There's nothing in it, but when you hold the black light, so this is actually giving out a lot of UV radiation And exciting it and then transferring it into the blue And also, what did I do with this so laundry detergent? It looks laundry detergent looks just like it You know like my lab coat does You can see his totally awesome glow in the dark skeleton of a bunny so So those are all just You know even these compounds aren't meant to be fluorescent, but they do Well, they're meant to be but I didn't want them to be right now Now everything's dark, and I can't see okay, so Yeah, so so those are just a couple small examples of photo-luminescence the the process that converts light into Another wavelength of light so So the joke is revealed. I didn't even say it yet So actually so going back to that compound avaben zone So in sunscreen what it actually does a really good job of absorbing it doesn't do such a good job of Re-emitting that light so that first a to a star it does a good job so I actually covered this piece of glass with with a sunscreen and Admittedly not a whole lot, but there's really no no blue color. No no re-emission out But you can play certain tricks with some of these compounds where you can add a secondary emitter You can have a star Hand off all this extra energy to something that does a better job of re-emitting it at another wavelength And so um in fact with that specific compound or actually one very much like it called So avaben zone if you put a europium atom Next to that chemical compound and you make one molecule out of it. You suddenly get a really intense So this compound you know what that's that's kind of yellow, right? So it's just a yellow compound. This is avaben zone with europium atom next to it And if I hit it with a really intense source of UV light You see the emission of europium Thank you for that. That really makes you feel good Yeah, so so what you're actually seeing now is not blue light But actually the red light from europium and europium is a lanthanide atom Just an element in the periodic table and actually the lanthanides end up having this really neat property of Giving out light and actually giving out light in all different wavelengths. So terbium, which you probably never heard of is green Disprosium gives I think kind of like a purpley color And some actually emit out all in the in the infrared so you can take a photon at 300 nanometers of light so outside the visible and then re-emit it all the way out at 1500 nanometers, so that's part of the research that I I'm actually working on this India but um, I Didn't actually bring this compound because it's phosphorus because it's photo luminescent It actually has another very cool property and that is mechanoluminescence. So Rick Could you start distributing these? So I'm what I'm passing around now just a couple so it's Some of that compound inside of a plastic baggy and then it's got two It's sandwiched between two glass slides. So if you so I'll explain a little while, but if you Just very lightly Press the two glass slides together. You'll see a little flash of that red light So make sure to pass it around get everyone around you to see it. It's hard to see it's a very it's a very You know dim light, but you can actually see it All right, and then after the talk, please go ahead and bring it up when you're done Please don't eat it although. European isn't that dangerous though With a name you like your opium, how can you go wrong? So mechanoluminescence so mechanoluminescence is the is the Luminoussence that results from a mechanical force on a compound and actually this compound has to be at least in The at least in the case that that you're seeing right now. It's a crystal so I came up with a with kind of an analogy for this that So imagine, you know Mike Tyson. He's totally ripped perfect human specimen. He's really strong You're not gonna beat him, but all of a sudden, you know, you get like a left hook you knock him out You break his teeth and He's really really pissed So that's mechanical force energy in You've you've excited him So now you have Mike Tyson with a little star like I had before so Tyson Tyson star And the only way that he's not going to be mad at you anymore is if he emits a photon of light All right, so that's not actually a good analogy But but the idea is there that so you have this perfect crystal this crystalline compound and In among all solids a crystal tends to be the most stable of the solid of the solid Compositions, thanks to And so if you disturb that crystal in lattice There's the possibility that you either break a chemical bond or you actually separate charge Kind of like you were doing with light that you're actually changing the electronic structure. So separating charge is an uphill in the potential energy scheme, so if You put if you put a crack inside this perfect crystal and now your negative and positive charges end up being Opposite one another the crystal will find a way either it puts a spark across a gap or the electrons migrate or or however It might work, but they'll find a way to neutralize that or to bring down that that high energy state that you've put in with your mechanical force and Some compounds like mechanoluminescent compounds like the one that you're holding now They'll emit light as that way of getting rid of that energy most of the time it would just be heat It would just kind of bump around with molecules around in the atmosphere But in this case you're going to give off a photon and in the case of these eropeum compound You're going to give off a photon about 620 nanometers. So a red light and that's and like a red orange light So, um, you know other examples that you can see this You can drop a pumpkin from like a second-story building in the dark and you should see tribal luminescent So a version of the can of luminescence If you go into your bathroom and you have a wintergreen crystal and you bite down on it With with your mouth open, of course, you can't see into your mouth You should see The sugar crystal so the you should see a little flash of like I think green light And that is a sugar crystal cracking, but it doesn't nest it doesn't emit a photon It transfers its energy to the the wintergreen oil that is in the in the in the um, in the breath mint and then that emits the photon for it similar to to the eropeum atom transferring at energy so All it's it's all around us and sometimes you just have to do weird stuff like biting wintergreen crystals in your bathroom with the lights out So this part is where you are still doing that Is everyone actually so if you have done this, have you been able to actually see the light? Okay, cool See the light. All right. Well, hopefully we're gonna see a lot more light in a second So chemiluminescent so as a chemist I saved chemiluminescence for last Chemo energy can be stored in chemical bonds in chemical compounds and If you allow so say if you allow chemical chemicals to react And they form new bonds and break old bonds Sometimes that and that energy doesn't all add up and you have some leftover Maybe you need a little bit extra in the case of a chemiluminescent reaction that leftover energy that you would normally see Is just kind of the solution heating up a little bit is actually instead of giving off as heat It's giving off given off as a photon of light So You know you see this in glow sticks In fact, I I sort of I I view bioluminescence as a a category of chemiluminescence It's a chemical reaction that's occurring but just inside a biological organism So sorry if that offends some biology people in the audience, but I it's just Biology can do a much better and more elegant job than any chemist can so I'll give that a little olive branch to you there So Let's see. So so now it's time for the actual Chemiluminescence so the the actual compound that I'm going to the two compounds the important ones I'm going to react are this one here called leucidin and It's going to react with hydrogen peroxide and that hydrogen peroxide is going to cleave this poor molecule into two But it's going to end up with one of these molecules actually having a little bit extra energy and a little bit extra energy in that Electronic state that those electrons aren't all situated in their most stable form where they want to be and so the best way to do To get back into that really stable state is to just emit a photon of light And in this case it's going to be a photon of blue light so All right, so with that I I'll just talk about so as with all good chemical reactions. Oh What you need to do is wear your PPE personal protective equipment Only splash a little bit So So I've got one solution of the leucidin and that is actually that is that is this compound here It's the sort of already fluorescent green color And I've got my solution of hydrogen peroxide Man my tonic and so Can I get these two lights here turned off? Or yeah, I think I think it should be okay I just want to make sure everyone can see because it is sort of it's somewhat subtle, but it's It's still awfully cool. So first. I'm just going to mix leucidin and hydrogen peroxide Now here we go. Hopefully this works So this is a chemical reaction. So it's going to take some time to react and so that but eventually all the Starting materials are going to get consumed and you're going to only see um and Then eventually the reaction will stop once all those energetic So the light is going to go out. Um, I know it's a very sad But uh, let's see. So so I'll mix this one up first the other Thing I'd like to do So in this one, I am going to now Mix so now I'm going to take do another thing where I add a secondary flora for a secondary emitter And hopefully you'll see a color change So first I do this and now I'm going to add this hopefully Maybe maybe there's a color change So I haven't actually changed the chemical reaction all I've done is added a different compound that emits at a different Wavelength that molecule that had all that energy it actually just bumped it over to the next molecule and It now gives off another another photon like and so I could probably even do it I've been do it with This one too. So it's starting to go out But now let's do it all so So so that is the conclusion of the chemiluminescence Demonstration and the conclusion of my talk. So thanks everyone. I hope you liked it any questions you might have Yep question over there. Ah So why is heat not allowed and I'm guessing you mean as the energy input? Um, so That's a good question. It's uh, so heat so When heat is applied and and you see light that's the that's a Form of black body radiation if you've taken plenty of physics or science courses like that that um the heat will Basically make any compound on the planet as long as it doesn't do some sort of chemical reaction It will make light and it's not necessarily that It's an electronic structure that you're not really moving electrons around to achieve this process That it just so that you're putting enough energy in that that you're getting this reflection of High energy radiation and as you turn up the heat as you go. So I think 798 Kelvin is the temperature. It's called the draper point where almost any compound like graphite You know rocks dirt that sort of stuff is suddenly going to start to glow red And as you apply more heat it you know moves further into the visible visible spectrum But in the case of luminescence, you're specifically exciting some electronic transition not just reflecting indiscriminate electromagnetic waves so Hopefully that hopefully that answer Yep Okay, so the question was what if there's a UV clear coat on the the window of your car Okay to protect the paint I guess so I think that works more like the sunscreen example that it doesn't necessarily Amit what it's really doing is just it's it's still sort of similar to a the benzone potentially I I don't really know so don't quote me on that but the idea is that it will absorb that elect that UV radiation and either Reflect it back or turn it into heat or do some other process that doesn't allow it to penetrate Into your paint and then cause your paint to photo bleach or you know, whatever process it does But yeah, so it's similar so that's photo luminescence not chemi luminescence. Yeah So glow sticks so glow sticks are chemi luminescent reactions In the case of glow sticks, so what I've shown is maybe a more general and easy to perform a reaction similar to how you might do luminol, but in the case of Glow sticks, it's just a different chemical compound In fact, I think from what I remember it is it's still hydrogen peroxide So again glow sticks are a sort of a tube within a tube that that's how they've separated the reagents I've just had to put them in two different, you know vials, but You then crack that tube you mix the reagents and the hydrogen peroxide reacts with a molecule typically called tcpo Which I actually I forget what the chemical compound actually is but you then have a second use then have the secondary emitter that kind of like when I added in that yellow compound that gave out the light and then They'll usually use that same mixture and then just change the color of the plastic coating to make you think that you're getting different colors But actually it's just it's just the changing the mixing of different colors to make to keep things cheap and to produce more But that's sort of the general principle similar to how I added hydrogen peroxide to my molecules Yep, I Would have to say no, I I Well, so the question was Can you have an endothermic or? Energy wanting reaction and a reaction that ends up sucking energy from the surrounding solution Also give off light, and I don't think that's a case because what you I I Guess I'd rather not paint myself into a corner, but I don't think I don't think that's true But I I could see Because what you're actually looking at is the electronic structure that results from the tip of the type of cleavage that you would be doing You know so you're cleaving that Lucigenin into one half depending on where the electrons end up that gives you the light out, but there could be it could still be Good question Good question. I would probably consider myself one of those, but yeah But that's okay, you insulted me and I'll take it. I've got my gin and tonic still More good right there. Very good question. So his question was Does the color of the emission so maybe in the in the context of the europium exactly so Again, just so you guys can hear it Does the wavelength of the emission change upon the oxidation state change of the metal atom? So Yes, it does it certainly does so in the case actually in the case of europium if you have europium 3 you're gonna see that red color You can you can reduce that compound to europium 2 and you actually get Not only a change in the fact that it that is a actually a phosphorescent reaction a phosphorescent emission We actually make it fluorescent upon changing it to europium 2 and it's actually a blue emission Am I right Patrick blue awesome. Yeah, so exactly because When you change your oxidation state you're actually changing the number of electrons that are surrounding that atom And so you're you're changing the electronic state of the atom and as I said This is all resulting from what the electronic state of the atom is in the first place So if you put in or take out electrons, you're definitely going to be changing which electrons are doing all the movement Sometimes it might not even be Luminescent in the first place. So I think you know so Serium 3 has one electron in its abalance. And so you're gonna move that around you if you oxidize it the serium 4 it has no more Accessible electrons and at least to excite in the visible range region. So it's no longer luminescent at least in the visible region Yep, that's a good question. Um, why why do your teeth glow in a black light? I actually don't know I I Could hazard a guess that maybe there's a fluorescent compound in the toothpaste and that you're just applying it to your teeth But I but you know there are plenty of of actual of rocks and minerals that are also fluorescent and Phosphorescent so I don't want to discount that as well, but that's a really good question I I don't know but I might think that it's all the tooth big toothpaste out there watching over us all But I don't know