 All right. Well, welcome everybody. Welcome back to the physics department speaker series. I'm Professor Steven Sikul, I'm the chair of the department of physics. And it's my pleasure to welcome everybody to this hybrid event. I think we're all looking forward to this getting back to actual normal, where we no longer need zoom but we do have a bunch of participants connected. And I want to talk a little bit about how we're going to manage this today. So for the people in the room, if you want to ask a question, it's simple, you can just raise your hand, Tom, you can call on them if you see them. But to help our friends connected online, I have a microphone. So just give me 10 seconds to run to wherever you are in the room. So you can ask your question and it can be heard online. So the folks online to avoid stray ambient noise from people randomly unmuting their microphones. We don't let anybody just unmute. But if you have a question, just type the word question or comment or something like that in the chat window. I'll be monitoring that from the laptop. And then I'll go ahead and let Tom know and we'll get you called on. You can also type your question in the chat window and I can ask it for you if it's clear enough to me. Okay. So before we get started today, I wanted to take the opportunity while we have people sort of connected in person and remotely to introduce one of our newest postdoctoral researchers, Xi Jing Zhang, who you can just come on down here into the camera view. So Xi Jing is, is joining us as a gym and she arrived just a couple of weeks ago. And she's joining the SMU Atlas group she received her PhD recently completed, and it was jointly conducted between I have been Beijing and I into P3 in France and Leon. And her thesis was conducted on the CMS experiment. So she has two culture shocks, one coming to the United States and moving here and relocating to Dallas and going from a high function collaboration to Atlas. Welcome Xi Jing. And she looks forward to making significant contributions to the Atlas physics program in the years ahead so let's let's give a round of applause to Xi Jing. So thank you. All right, so without further ado, I'm going to go ahead and introduce our speaker today. And I forgot to ask you this beforehand so I'm going to hack it right here to be in Tom run chef. Yes, correct. Yes. Okay. So Professor Tom run chef ski is going to be our speaker today. He's going to tell us about Titan in a jar. Now he was born in Macedonia, where he finished his undergraduate studies and chemistry in 2011. And he earned his PhD at the Max Planck Institute for solid state research and Stuttgart, Germany, with Professor Robert Eden of higher. His graduate work was on structural characterization of materials with diffraction and spectroscopic methods with the focus on structure solution and refinement of polycrystalline materials. He graduated in 2014 with honors, and was awarded the auto hot metal of the Max Planck Society. And after a one year postdoctoral stay at the Max Planck Institute. He joined UC Berkeley and the Lawrence Berkeley National Laboratory in 2015 as a postdoctoral researcher with Professor Jeffrey are long working on characterization of porous materials. In 2018, he started his own independent career at Southern Methodist University as an assistant professor of chemistry. Let's welcome him today to give our and all your coworkers. Thank you. Thank you very much for the introduction and it's really nice to present in a different department but the same school. So we can finally meet officially. Before I start the presentation. I have to say that what what I'm going to present today is basically one third of what our group is doing. Today I'm going to talk about Titan Titan jar a little bit poetic title but I promise there is not as much poetry in the talk. Besides of that we do work also in the field of material science, particularly sports supplements so if someone wants to go in bodybuilding, that's something that we do as well. And recently we started working with antibiotic glasses, and someone wants to make antibiotic glasses that it's another venue of research of ours quite recent. So today, I will present what we've done on Titan, something smooth, which I think is quite suitable physics chemistry and planetary research they they are intertwined. They, you know, we work towards the same goal. And I think there is a lot of overlap overlap between the research that goes on Titan from the site of chemistry and from site physics. Okay, so Titan, when I say Titan, just to make it clear, I'm talking about Titan southern smooth Titan southern smooth is an extremely interesting place. And we know a lot about it. Thanks to the Cassini Huygens mission that concluded just a couple of years ago. So Cassini Huygens was a huge mission that explores Saturn's in this moon and there are just some basic facts about it. This mission landed on Titan collected a lot of data that's how we know about this moon. This one is so interesting that NASA decided to send another mission to Titan in just couple of years which is called the dragonfly. And this is the dragonfly rover. What is a little bit different than in this mission compared to others is that the dragonfly rover will go on Titan it will stay for a couple of months. It will just fly by will stay and it will fly from the desert into the into the lakes and then crater. So it will explore the moon quite quite a lot. It is expected to touch down in just couple of decades so in our lifetime. So, if you ask me now is there now is the time to do research on Titan because charging play will arrive there in a couple of decades, the moment when I plan to get retired. But between now in my retirement, I would like to make some contribution with our group in helping this mission, and in general helping to understand how does Titan look like. Okay, so before I start presenting our results and findings. Why Titan, and, you know, for those of you who are not familiar with the moon. What is so interesting about that moon. Well, Titan is the only other place in our solar system that has dense atmosphere, and it has also liquid on surface there is no such a place in our solar system that we know of the atmosphere is made of predominant nitrogen and methane. We have the lakes, the lakes of Titan, which are made of methane methane and propane. There is a lot of going on this this picture which I took from NASA. It actually shows quite overwhelmingly what is going on Titan and I will try, I will try to put this very simply with the most important things that are going on. So the first thing that happens here in the upper atmosphere is we have a lot of chemistry, filled by the magnetosphere of Saturn, and of course the sun, we have a lot of organic reactions that take place. Nitrogen and methane react as they react they produce methane methane and all of this other chemicals that you see everything that has been produced, it's carried by methane methane on Titan plays the same role as water on earth. So basically the same cycle hydrological cycle that we see in earth, we can see on Titan, however, now we have methane, we have methane that evaporates from the lakes to the atmosphere in the cycles. As it cycles, it is carrying on all of these chemicals, all of these chemicals to the surface. Also this chemicals with would concentrate in the case that's how we have that titanium case. It is quite interesting to notice that we have rain of methane that that must be very fun to watch. And not only that we have rains but their their evidence is that we have storms of methane. That's something that is quite interesting to imagine imagine a storm of methane and then hear hurricane of methane. Anyway, so that hurricane and storm would go down and will touch the ground. As it touches the ground, all of these chemicals will either touch a solid or they will get dissolved in the lakes. Interestingly, only only nitrogen methane ethane and propane would be liquid or gas on Titan. Everything else would be solid. So all of this organic molecules that we see here are solids. By definition, if something it's naturally produced and solid, that's a mineral. So if if we say that benzene for all of us or I see the nitrile there are just simply chemicals that we have in every laboratory. That's for us that's from our, our point of view but on Titan, they are minerals. And that's what we call the minerals on Titan. If you want to learn a little bit more about it we recently published an accounts of chemical research that summarizes pretty the recent the recent results from our lab and the lab in NASA, working on this perspective minerals and minerals on Titan. Okay, so why do we as chemists are in the right place to study Titan. As you can see here, the moon, which was one of the first, first places of humankind to, you know, to visit. Next Mars, they both and many other comments are composed of common surface minerals in organic silicates with Madagrox and so on. But Titan is completely different. Titan has an organic surface and has organic surface minerals. There's a reason why now is the time for physical chemists to shine. As you can see the propion nitrile acid and nitrile benzene, again, simple chemicals for all of us but minerals from Titan, and we can really help do a lot of, you know, help help understand Titan much better if we take a look on the solid state chemistry of all of this materials. What can we learn and why, why we are interested in exactly this molecules. Well, there are a lot of references and I just, I just put them there, but let's go step by step and and introduce some of the possible areas in which we can make contributions. First of all, detection of minerals on Titan, Cassini collected a lot of data. The interpretation of the data is extremely challenging. And it makes sense that data is remotely collected. The haze is very dense. So everything that all of the old probes that touch Titan's ground and collected data would be really difficult to be analyzed, only benzene so far has been unambiguously determined as a mineral on Titan. Acid and nitrile for example, it's only tentatively that remind and it's it's it is known that it exists in Titan, but it has not been detected on the surface. Now, one hypothesis. Why and first of all, when I say, when I say this is debated, it's debated in the following way. Cassini collected spectroscopic data in the way how you analyze spectroscopic data and is here matching with standards collected on Earth. To match the the peaks of the pseudo nitrile. There is a small misshift, and that small misshift. It's enough to say, okay, we believe that there is a pseudo nitrile, but it but there is a misshift so you cannot be 100% sure that this is a pseudo nitrile. So how can we help a pseudo nitrile as solid has been compared to whatever whatever data has been collected by Cassini, but who says that the pseudo nitrile will be molecular solid in Titan we know it will be solid, but we do not have any that is going to be a molecular crystal. Your physicist so just just a crash course in solid state chemistry molecules can exist as molecular solids, but it can also exist as hydrates in which we have crystallization with water molecules. And hydrates in which we have crystallization within the framework of ice, and they can, they can form co crystals, co crystals are basically crystals that are composed of two different organic molecules. So who says that if we have a pseudo nitrile in the atmosphere and touches down the lakes, it will crystallize molecular solid, especially that we know that we also have benzene. Now, if a pseudo nitrile and benzene combined, and if they form a co crystal that co crystal will have unique spectral signature, which will be different than the spectra of benzene and pseudo nitrile. The differences will be subtle. So it will be small blue or red shift of the of the of the peaks, enough to jeopardize the identification of the mural and enough to enough to to to put some doubts. So that's sort of the reason why we can, we can really work and help identify minerals and Titan. Very similar propion nitrile propion nitrile is been really debated, not only on the surface but also the haze. I see the nitrile has been identified propion nitrile has not been identified, even in the haze. The similar similar logic and similar story might be told for here's propion nitrile might be told for propion nitrile this might be the reason why we have not identified. And so, which really inspired us to go in and look in combinations is all of the proposed synthetic routes in this papers for the synthesis of a pseudo nitrile and propion nitrile. If you follow the synthetic routes, you follow the equilibrium, you will see that the energy barrier between the synthesis of a pseudo nitrile and the synthesis of propion nitrile are very near and the energy very server shell, and the and the synthetic routes are there. So our logic is, if you have a pseudo nitrile in the system, you probably have propion nitrile and vice versa. That being said, it makes more sense to study them together in a mixture, then studying them separately for a lot of people. If you study something separately and in the mixture doesn't make that much of a difference but for solid state chemistry makes a huge difference. And the second part of my talk, so the first part will be a system actually in benzene and what we can learn about that combination and the second part of the talk would be the composition of a mixture and how a mixture can can change the properties of the system. Okay, let's start first we start with this two molecules. So if they exist in Titan, we have identified them in the atmosphere, and they will touch down on Titan, they will get dissolved in the lakes. The solubility constant of both of them in ethane are very low so they will crystallize. So let's see how they will crystallize and how they will form minerals. And this is a reminder, this is a phase diagram for mineral on earth. Earth is predominantly made of minerals like this. So you have calcium, silicon aluminum and we have all the oxides. All of this are minerals on earth, and this is how the phase diagram looks like incredibly complicated. Our goal is to do similar phase diagrams, but for pseudo nitrile and benzene. Again, that makes sense, because what is on earth silicon, you can imagine that to be on Titan benzene or aluminum pseudo nitrile. The correlation doesn't go that simple, but you get the point what we want to achieve. Okay, how do we make this phase diagram? There are two ways. There are actually many ways. First of all, we can look at crystallization, but that's not a good idea because crystallization can be a stochastic event that may be determined by even impure. If you have a seed of crystal, you will have crystallization so it's not thermodynamically driven. On the other side, melting is, melting is a very thermodynamically event. There's a reason why we decided to look at the melting peaks on the endothermic peaks of mixtures of acetonitrile and benzene. What we have here, we have prepared a couple of mixtures and Pristina did this here in our lab. We have mixtures starting from pure benzene to we go up to pure acetonitrile and all of those combinations. As you can see here, we have different endothermic peak maxima, minima in this case, that are shifting and as they are shifting, they are outlining the phase diagram of acetonitrile and benzene. Looking at this peak minima, we can plot the phase diagram. This is the solid-liquid phase diagram of acetonitrile and benzene that has been created in our lab and here below, of course, would be the region that we as chemists would be interested for Titan. Okay, let's take a look now on the phase diagram and what we can learn by the phase diagram. Well, we can learn a lot. We can, for example, learn that here we have a fusion line. Here we have one solid and one liquid phase. This is this part. This is a fusion line. Then we have here probably two solid phases, here one solid, one liquid, here also two solids. But as we can see, we don't really see what is inside and this does give us a lot of information, but it's not enough. And it's just lines. We just know where the phase transformation will happen, but we have no idea what is going on inside. Of course, here we have one liquid phase that is easy, but this place of the phase diagram is really complicated. If we really want to study what is going on in the phase diagram, we need some structural evidence and some structural probe. The way to go is we're taking these isoplets. In these isoplets, we need to collect data as a function of temperature, cover all of the phase regions with some spectroscopic or diffraction or diffraction technique. There are many different techniques that we can work on. Arguably, the best one is X-ray powder diffraction. The reason why it's the best one, X-ray, as a probe, is quite fast. You can be collecting data for a couple of seconds if you use synchrotron radiation. On the other side, powder, it's easier because you don't have the need to grow single crystals, large single crystals. The sample preparation is very easy and the handling of the samples is also very easy. We did exactly that at the synchrotron at Argon National Lab. We can do this in the lab here at SMU. We do have the equipment. However, one set of data will take us 24 hours at Argon. One set of data takes us a couple of seconds. So basically, we can collect all of this data at SMU, but the data collection will be done by the time that I will need to submit my tenure track package. That's not going to work. That's why we went to Argon and we collected data within just a couple of hours and we covered all of the face regions. Okay, so here I will present just one set of those data and one we can learn about them. So we are going here and we're cooling down. As we're cooling down, we are touching through all of these face regions and we're collecting data. This is how the data looks like. So here is the temperature scale and here is a two-theta angle. A two-theta angle, as you know, is the signal from the x-rays and this are the bands. If you take just visually a look on what kind of this two-dimensional plots are showing us, we'll see here that we have extra peaks because we have here two solid phases. Here we have changes which corresponds to this place here and here we have no peaks because this is liquid and liquid do not give coherence scattering of x-rays. The next thing that we do is analyzing the data on each of these regions. This data analysis is relatively difficult. For those of you who are experimental physicists, you might know, solid crystal structures from single crystals is very straightforward because you have a single crystal which is a three-dimensional object and you're collecting data in a sphere which is also a three-dimensional set of data because of that you have a straightforward mathematical problem, three-dimensional data and you have three-dimensional solution. On the other side with powder patterns, as you can see, we have one-dimensional data that spends on the two-theta axis. So we have one-dimensional data but we have still three-dimensional problem to solve. That being said, this is an extremely challenging thing to do and there are only a handful of research groups that are doing this type of analysis. Not only that we are able to do this analysis but also we are able to do face mixtures and simultaneously determine the crystal structures of a couple of phases in the pattern and by doing so we can really see what is going on in each of these regions. As I said, here I present just one isoplet but that can be done in each of these regions and we can cover the whole part of the face diagram. By doing so we can solve the structure and this is how the structure looks like. So in this area I'm just showing one face transformation and as we can see this is pure benzene. In this region we have solid benzene. Acidonitrile is in liquid form and that's why we don't see it. Here Acidonitrile below this face line is reacting with solid benzene which is called the paratectic reaction or paratectic phase transition and it's penetrating into the crystal structure and it's forming a co-crystal. In this case we have two phases. One is the unreacted benzene and the other one would be the co-crystal that we assume that we will find. By doing so not only that we are able to look at the face lines and see okay we have a face line and we have different face regions but with combining these different techniques we are able to really see what is going on in each of these face regions. So as we can see here in this region we have solid benzene and this is the face stability region of benzene under these conditions. At this place, this part of the face diagram, not only that we have benzene but we have the one to three Acidonitrile benzene co-crystal. In this region here we have beta Acidonitrile, here we have alpha Acidonitrile and of course this is just liquid. So these are the solids of Acidonitrile and benzene. The most notable one for Titan would be the fact that Acidonitrile and benzene would form this type of co-crystal. The next step in our research which we have not done but definitely the natural progression would be to study the spectral signatures because this co-crystal might have that misshift and explain the identification of Acidonitrile and solve quite long standing problem in the structure of Titan. But there are another ways of how we can use this co-crystal to study Titan. So these are the lakes of Titan and one extremely interesting thing about it is the cycling. The lakes are known to evaporate and then precipitate and form lakes again. So you can learn a lot about the history of Titan if you know at which parts there was a lake and which part there wasn't a lake. So the existence of this co-crystal may serve as an indicator for past or future presence of ethane because of the following. We realize that when we have contact with ethane the structure of this co-crystal is changing. We don't yet know because this powder patterns are so complicated to be analyzed and we are working in that direction but the patterns are changing. So as you can see here we have peak splitting upon contact with ethane. Even though that we don't know now the structure of the co-crystal this is still relevant as an indicator for past presence of ethane. For example, let's say that if tomorrow we identify this peak splitting on the surface of Titan which is dry that may indicate that sometime in the past there was ethane and there was a lake there. I do think that it is quite useful for the future analysis on Titan. There is another way how we can look at this data and how they can be meaningful in the genesis of Titan that is the ethane ocean problem. And that's the name of the problems, the ethane ocean problem. Based on simple calculations of how much ethane is being constantly produced and the atmosphere of Titan. There should be an ocean of ethane on Titan. When Cassini flew by it did not see any ocean and you know ocean is not something you can easily miss. It's huge, it's ocean. You should see it but Cassini did not. One possible answer why there is no ocean is maybe sequestrating of ethane in a form of co-crystal. So in this case if ethane really penetrates this co-crystal then instead of seeing an ocean or liquid of ethane it may be sequestrated similar as it for example creates a solid and that's the reason why we would not see it on Titan. And there are other ways of how we can use this knowledge to learn a little bit more about Titan. We also featured that on the cover of Chemcom. This is Dragonfly, it will not be this beautiful, it is just an artistic representation of how we would look at it. Okay, so that was the first part of the presentation and now we'll jump on the second one. We'll focus on the first one, acetonitrile and benzene and we'll focus on this part here. On the logic that if we have acetonitrile we'll probably have propionitrile in the system and vice versa. So we'll have both of them together. So far they have been studied, separate one from another, but as you can see a lot of things are changing when they're together. Okay, let's start step by step. The first one, the propionitrile acetonitrile. What we know about it is that we have two polymers, the high temperature polymorph and the low temperature polymorph. And there is a phase transition between them. So here we have liquid crystallization and high temperature polymorph. This is the place where the high temperature polymorph stable and then polymorphic transformation to low temperature. Propionitrile has the same. The difference is that the crystal structures of propionitrile were not solved. And that is quite surprising. This is propionitrile, it's only a couple of atoms. The fact that we didn't know the crystal structure of propionitrile in the 21st century is shameful. We know so many complicated things but not to know the crystal structure of one of the most basic molecules is again shameful. For us as chemists, for you as a physicist it's a little bit better. The crystal structure was reported on the low temperature polymorph in 2020 by the time that we actually have solved it. We were scooped. That was one of the worst days in my life. However, it happens. The reason why we haven't published and we still haven't published is because this article here presented just the crystal structure as I will present. We collected a lot of data because we want to present a comprehensive overall study on propionitrile and acetonitrile followed with diffractions, but just could be total scattering, nutrient analysis and so on. So we waited and that paper should show up anytime, anytime soon. We also solved the crystal structure of the high temperature chemicals, but in general for simple chemicals like this just to figure it out of his diagrams. Very fundamental, very simple science. But it does give us a lot of information in a lot of interesting data on the behavior, the phase behavior between these two chemicals. So we have the phase diagram, what we can do with it and how we can correlate it to Titan. Well, there are a couple of things. Let's start with one of them. So here, what I present is, as you can see this familiar picture that I showed. So propionitrile and acetonitrile would be synthesized somewhere here. And then they will just go down. And here what we have is a temperature plot. And as you can see in the mesosphere up in the stratosphere, we have relatively high temperatures. So here those temperatures start going down. As they're going down from around here to around here we have the haze layer. So the haze layer, this is the haze layer, forms because the temperature goes down, the molecules condense. Makes sense. As they condense, they form aerosols, as they form aerosols, we have that characteristic haze. And this is that haze layer. And then the temperature goes actually a little bit up and it touches down. So let's take a look in this part. We have a drop of temperature, which is quite significant. And this is the phase diagram. Why and how are these two related and how this can help Titan understanding the structure of Titan. Well, take a look. We have around 60 Kelvin difference from the top part of the layer to the bottom part of the layer, and that corresponds to 50 kilometers in altitude. Look at the phase diagram. If you take a look only on a pseudo nitro, which is not mixed with with propion nitro, it will crystallize around here. And look, if you mix it with a pseudo nitro, the lowest point of crystallization will be the tactic point, and that the tactic point is it's around 60 Kelvin lower than the crystallization of pure pseudo nitro. That means that if we have it mixed, this difference of 60 Kelvin may translate to to 50 kilometers difference in altitude. And this is important because, as I said, for example, propion nitro is not being identified in the case. We may be looking at different altitude we might expect crystals of this nitrials at certain altitude but because they're mixed, and they're not alone in phase pure, we may encounter them in a different altitude and this is just a mixture of two but you can imagine Titan is the mixture on a planetary scale. So we definitely need to work a little bit more in the direction of figuring out what is going on. As I said, we can get all this information just by looking at the boundaries, but very similar to the case of propion nitro and pseudo nitro we really don't know what is going on here. The only way how we can learn is doing the fraction and solving all those crystal structures. And this is exactly what we did. So we first followed pure pseudo nitro, then pure propion nitro, and then went ahead to go and cover the rest of the phase diagram. And as I said, a lot of these phases are unknown. So let's talk about it. Let's talk about pure pseudo nitro. These two phases have been known for a couple of decades now. What we know this and it's quite interesting is that when we cool down the system, we have quenching of the monoclinic high temperature phase. One of the differences we would expect when we cool down to have first the high temperature form, which is monoclinic, and then phase transformation into the orthorhombic low temperature form. We do not see that. And the reason why we do not see that it is strange but not that strange that is just kinetically trapped. And we have the low temperature form being stabilized at the high temperature form being stabilized at low temperatures. So looking up, we are giving the system a little bit of notch so it can really go back and get this phase transformation to the low temperature form. Then another phase transformation to the high temperature forms. There is a little bit messy here. And then, finally, we have nothing. What we learned from this experiment is that, sure, we have the high temperature and the low temperature form, but there can be switch between them based on whether the crystallization is under more thermo than under control. How is this relatable and why is this important for Titan? Well, on one side, we can say that if a system actually cools down and rains down quite fast, we can have this quenching. Then the next question would be, will the high temperature form stay high temperature or monoclinic throughout time? There are two arguments there. On one side, it's quite cold, so it's very difficult to have a phase transformation if you don't have that energy input. Think about glass. Glass should not exist because it's metastable form. It should crystallize. Yet glass doesn't crystallize. We all use glass. So similar thinking happened with the Cedron-I-Shell. On the other side, we're talking about perpetuity. So eventually, there might be the phase transformation. That is quite interesting argument to be made. And future experiments are needed to figure out what is going on. And it's also interesting to figure, to follow why this phase transformation is trapped and why it's kinetically controlled if we take a look on the structure of the Cedron-I-Shell in liquid. The structure in liquid, which was solved by PDF, it is very similar in the high temperature form. Here, as you can see, we have that head-to-tail type of orientation, head-to-tail. So in order for the high temperature form to go to the low temperature, we need to have switch of this head-to-tail to head-to-head transformation that requires a little bit of energy. That's the reason why we have kinetic control of the high temperature form. We also follow this type of experiments with our lab. And in our lab, what we do is we take total scattering data and by doing the PDF analysis, distribution function, we can figure out the liquid structure of the system as well. Okay, propion-I-Shell now. Propion-I-Shell behaves a little bit more logically under our conditions. When we are cooling down, we have the high temperature phase crystallizing as expected. Then we have the phase transformation to the low temperature form. And once it's heating up, we have, again, the high temperature form. This one was solved and we were scooped by this two are not solved. We're not solved. We sold them and we're looking for republishing all this data together. As I said, things are working out a little bit more logically here. It is interesting to see that a pseudo-I-Shell has this quenching. Propion-I-Shell doesn't. That just shows us how complicated this small molecules can be. And it's the same with propion-I-Shell and the pseudo-I-Shell. We have also that head-to-tail type of structure in liquid, which is very similar to the one that we have in the high temperature form. But as you can see, similar type of structure we have in the low temperature form as well. And that might be the reason why there is not that much of quenching, meaning it is very easy to go from this polymer to this one as opposed to a pseudo-I-Shell in which flipping of whole layers should occur. This is how the patterns look like. We also notice quite interesting structural effects in these two polymers, but we don't really have time to talk about it. But we will move to a mixture. When we have a mixture, we have really complicated behavior. First of all, if you remember, I said that a pseudo-I-Shell is getting quenched when it's pure. For some reason, when it's mixed, that quenching doesn't occur. The high temperature form does not even exist. It's directly go to the low temperature form. On the other side, proprio-I-Shell is now quenched. Now we have the monoclinic form of proprio-I-Shell being quenched and the orthorhombic form of a pseudo-I-Shell. When we are heating up the system, we have, again, interplay of the phases. Long story short, this is extremely complicated and at first it does not make sense. But if you think about it, all of these phases that exist, the energy minimum are very related. So it's very easy to go from one structure to another. It's very easy to have quenching or not to have quenching. If you have a mixture with the sole existence of one phase as a crystal, it can look like another phase on top of it and by that you can have a completely different sequence of polymers. The take-home message is, if we want to guess what kind of structures we will have on Titan when we have pure or mixed pseudo-I-Shell and proprio-I-Shell, it is an utter mess. And we can make assumptions what would be the most stable one. We can say, okay, the pseudo-I-Shell in the orthorhombic form might be the most stable one because that one has been quenched and stable and in perpetuity should not transform to anything else because it's a thermodynamically stable form, but what would be the second most likely structure on Titan we don't know yet. And that is important because as I said, we have to compare the spectroscopic data that we collected on Titan with laboratory standards. So are we comparing with this one, this one or this one? And it's quite complicated and it's important in order to really see what's going on on Titan. And before I conclude, let's go and talk about basically the solid-state chemistry on this mineral, so this materials and what we can learn from them. We decided to present four different things that we focused on. We can learn something about them. And first we will focus on thermal expansion and potential influence particle size on Titan. This is the thermal expansion of a pseudo-I-Shell and proprio-I-Shell, whether they're mixed or whether they're alone. So thermal expansion, well, you probably covered that quite in a different aspect that we do. It's basically the response to the solid-state on temperature. Normally, when you heat something because of vibrations, things are expanding, hence thermal expansion. But if we take a look, we have quite interesting behavior of a pseudo-I-Shell and proprio-I-Shell and this might be a little bit of a better representation on the thermal expansion. So first thing that you can notice is a very pronounced anisotropy of thermal expansion, which is not very common. Commonly solids would expand in every direction pretty isothermally. But in this case, because of how the crystal structure looked like, they expand completely anisotropic. Moreover, proprio-I-Shell, the metastable form, high temperature form, the monoclinic, is featuring also negative thermal expansion. It's uniaxial. It's uniaxial, negative thermal expansion is unusual, yet it's understandable from a structural point. But it's quite interesting. And now why is this interesting for Titan? For us, this chemist is great because thermal expansion is something we can use in functional elements, and it's very important to understand the structure of solids and so on. But why should we care in regards to Titan? Well, here, from the hazelayer, where we may have these crystals form, from the hazelayer, they would need to descend and touch ground. As they are descending and touching ground, as you can see here, the temperature is actually increasing and the temperature here is decreasing. So as the temperature is increasing and decreasing, also on the surface of Titan, you have cycling, and during that cycling, you have differences in temperature. The differences in temperature would cause crystals to expand and shrink. If this shrinking and expansion is anisotropic, it can easily lead to fracturing of the crystals. If you have fracturing of the crystals, the spectroscopic data that you're collecting will be influenced by that fracture, which is completely normal, because the scattering will be different from fractured surface compared to the nicely polished surface. And that might explain why we see Titan the way we see it. It might be very, very fractured. Again, further theoretical analysis in this case are necessary to really understand how this fracturing works. Okay, next, the macroscopic structure and how this can be potentially related to life. There is a paper which is quite interesting. It's quite recent. It's a very important member in self-assembled Titan. So polar structures are important for the origins of life and how these minerals can really help in this in this direction. Well, I will not go in detail, but we also saw the structure from single crystal and having combined powder and single crystal together and analyzing the preferred orientation. We can really learn how the crystal will look macroscopically and which faces would be exposed. And this is quite interesting and quite important because as you can see here, this are the preferred orientation of cases of propionageal. And some of these faces are polar. This polarity can actually help and have influence in potential, of course potential, origins of life type of scenario. If we have a polar surface that can help grow and self-assemble other molecules on top of that surface. This is one of the theories how life on earth started. Of course, we don't work in that direction. I'm not saying that we're working in origins of life type of research, but what I'm saying is that figuring out what is the mineralogical makeup of Titan might help that research as well. Next vibrational structure. As I said, I mentioned a couple of times why vibrational structure is important. And we do research in that in that direction to what we what we work is we collected the Raman spectra. We were collected at our national lab with with Raman's Raman probe that it's not. There was just a remote sensing so that the quality of the spectrum is not very good. We're not able really to tell the difference between different polymers and between the co crystal and so on, because our data was not, you know, very high quality. Thanks to NSF and the new MRI funded project at SMU together with the Lyle school, we got a Raman spectrometer which will arrive and be installed at SMU in just couple of months. So I'm really looking forward to doing this experiments and figuring out how high resolution Raman data would look like. Even though we have the low low resolution data we can still analyze we can still learn a lot about the spectrum. This is quite interesting. You can see this is the calculate the spectrum of propionage in gas, but the experimental spectrum is quite rich. And it doesn't really explain all of the bands. The reason why is even though these molecules are so simple, not only that you have the fundamental vibrations but you also have first overtones and you also have combination combination modes and together with Elfin with mainframe here where we were able to really explain by DFT how all this fundamental first overtones and combinations work. Excellent exercise for those of you who like a group theory to really calculate from scratch of how these vibrations will go. I did my masters in Macedonian. Most of my professors were very much into that into calculating the group theory, how what kind of shifting there will be quite simple yet powerful mathematical concepts. So feel free. There's that kind of analysis will not give you this beautiful gifts of how this vibration happen and if you have DFT you can really learn a little bit a little bit more about how really this vibration happen. You can visualize them it's not just the pleasure of solving mathematical equation and masses but also visualizing them and see that they're real they're not imaginary. I'm also very excited to present this data that were collected just two days ago. This is the data that were collected at Oak Ridge National Lab. So this is vibrational nuisance spectroscopy now this is something different. The Raman, as you know, the Raman spectroscopy uses photons to excite and to collect the spectra vibrational nuisance spectroscopy does absolutely the same, except doesn't doesn't use photons, but nutrients. That is quite exciting. The reason why when we have interactions between photons and the election cloud, we have a lot of problems in the data analysis. But if we have interactions between nutrients and the nucleus, this should be very straightforward for calculations. Having that in mind having that ease of calculating, we're able to really explain the system much much better than using using Raman spectroscopy. That's that's a beautiful technique. The problem with this technique is it can be done only a two three places in the world. So it's not very common as you can just go in the next door and then collect data, but I'm very very happy to have the collaboration with Oak Ridge. They are now very excited some as I'm looking forward to collecting more and more data and establishing a really solid solid collaboration with them. Okay, and finally, I will go and talk about dynamics. When people think about crystals, they think about their static and they don't move I think about rocks, but that's not true. We think of crystals as solids just because it works in our favor, because then we can neglect the dynamic structure, but should we do that. No, we should not we should also look at dynamics. How should we do that so this is the this is the plus elastic nuisance scattering spectrum. There's you can see here we're cooling down. Here we have, we have quite much of a mean standard deviation of the high genes in various forecasting and being random because this is liquid, which makes sense. But then, if everything is static and there is no movement. So the crystallization here we should have drop fine we have that drop, but that drop should go to zero. But it doesn't. From here, it takes up to 50 Kelvin and of course here is zero because here we measure data down to five Kelvin and five Kelvin nothing moves. But above above 50 Kelvin, especially about 100 Kelvin, we have a lot of movement. So that means that not only that we have movement but that movement is significant. So if we analyze the data that we have the data, this is the partial fit with and without the Laurentian fact function, the luncheon function can give us information about the movement. And it can really help us calculate the jumping if, and what kind of dynamics we have if we collect data a couple of plots by doing so we realize that in in in preparation I show this metal group is actually jumping and this is perpetually and that threefold jump happens at 1800 picoseconds time scale in perpetuity under conditions of Titan is quite important. Of course, for us might for purposes on earth might be insignificant, but when we're talking about Titan this might be significant and we're talking about potential life on Titan this might be significant because again, when when not one of the reasons does not sense the giant flight is the origin supply story, but no one expects on Titan to find Starbucks and life like we have the life on Titan would be different. And this type of movement might be energetically enough for to you know help help that kind of that kind of story about the origins of life. So, I will conclude now so we can have some, some time for questions. In the center national and benzene we show that with DSC and peaks really combined to parameter in the fraction we can really get the face the face diagrams we can correlate that with with Titan learn a little bit how the simple yet interesting studies can, can, can, you know, teach us something about the moon. The same goes for the center national appropriate national. But actually, if I really have one one concluding sentence that I will say that the research and Titan has just started. The three molecules that we talked about their 30 that are detected. Nothing is known for most of them, and those are those that have been detected. Titan is a moon, Titan is not small little jar, but it's this, it's, it's laboratory planetary skill. And now is the time to really analyze and make the systems more and more complicated. Finally, acknowledgement. We have this type of research has been cannot be done without the help of large scale facilities, because of the experimental techniques. So we have the help from missed argon Oak Ridge for neutral diffraction and make sure the fraction until scattering and vibrational at NYU we did the single crystallic trade diffraction analysis, and also mainframe for the theoretical calculations. And finally, to acknowledge research group and funding from the world foundation and from NASA. And thank you very much for your attention and for the invitation again.