Research Spotlights

By Georgia Barrington-Smith

In the quest to unravel one of life’s greatest mysteries—how it all began—scientists are looking beyond our planet, to the vastness of space, in search of the molecular seeds that might have sown life on Earth.

One key stop on that journey is Titan—Saturn’s largest moon.

For nearly two decades, NASA’s Cassini spacecraft orbited Saturn, collecting stunning data about the planet’s rings, moons, and magnetic environment. Accompanying it was the European Space Agency’s Huygens probe, which parachuted down to Titan’s surface, becoming the first spacecraft to land on a world in the outer Solar System.

What it found was astonishing!

This mission revealed that Titan isn’t just a frozen, foreign world, it’s a chemical treasure trove. Its atmosphere contains more than twenty complex organic molecules. Among the most intriguing are nitrogen-rich compounds that could serve as stepping stones in the formation of prebiotic molecules, the very kind that may have paved the way for microbial life on early Earth.

How Titan’s co-crystals could hold clues to life’s beginnings

New research suggests that Titan’s icy temperatures and dense, organic-rich atmosphere create ideal conditions for the formation of co-crystals: solid structures made up of two or more molecules arranged in a fixed, orderly pattern (Cable et al. 2021). These ordered molecular arrangements provide a scaffold that allows close interactions between complex compounds, providing stepping stones toward biologically relevant molecules.

Therefore, studying these co-crystals, which can stabilise these fragile complex molecules, is critical for understanding how prebiotic chemistry (the chemical processes that generate life’s building blocks, such as amino acids and nucleotides) develops and survives in harsh extraterrestrial environments.

One compound of particular interest is pyridine, a nitrogen-containing aromatic compound thought to exist in Titan’s atmosphere. Pyridine interacts with hydrocarbons like acetylene to create stable co-crystals, which are believed to act as precursors to nucleobases (the building blocks to DNA and RNA). This makes pyridine a promising candidate for exploring how co-crystal formation might contribute to prebiotic chemistry on Titan.

Larissa investigates Titan’s prebiotic potential

Larissa Lopes Cavalcante, an AINSE PGRA scholar, in collaboration with ANSTO and the University of Otago, is investigating pyridine-based co-crystals and their potential role in forming prebiotic molecules. Her research focuses on combining pyridine with key molecules found in Titan’s atmosphere, like acetylene, diacetylene, ethane, and acrylonitrile.

By using techniques such as X-ray diffraction, infrared and Raman spectroscopy, mass spectrometry, and computational modelling, Larissa aims to characterise these co-crystals and uncover the pathways that might lead to life’s building blocks.

Simulating Titan’s atmosphere to explore prebiotic molecules

One focus of Larissa’s research is the pyridine: acetylene system, previously shown to form stable co-crystals under Titan-like conditions. She studied the reactivity of this mixture under such conditions to determine if it can give rise to more complex organic molecules.

To test the systems reactivity, the team exposed both amorphous (disordered) and crystalline (ordered) pyridine: acetylene ices to vacuum-ultraviolet (VUV) radiation, simulating the high-energy conditions in Titan’s atmosphere (Lopes Cavalcante et al. 2024).

Under VUV exposure, pyridine and acetylene reacted to form nitrogen-containing polycyclic aromatic hydrocarbons (NPAHs)—complex molecules that may serve as intermediates in the formation of life-related compounds.

Interestingly, the crystalline co-crystal form showed lower reactivity than its amorphous counterpart. This greater chemical stability makes it better equipped to withstand Titan’s extreme conditions. Maintaining the stability of the co-crystal is crucial for preserving pyridine, a key molecule in prebiotic chemistry. Once the co-crystal reaches Titan’s surface, pyridine could be released and become available to interact with other chemical species present there. Even more intriguing is the possibility that these surface molecules could be transported to Titan’s subsurface ocean, where conditions may allow for more complex, Earth-like prebiotic chemistry to unfold.

The role of pyridine: diacetylene in Titan’s prebiotic chemistry

Larissa and the team also explored the pyridine: diacetylene system for its potential role in Titan’s prebiotic chemistry.

Diacetylene, a hydrocarbon abundant in Titan’s atmosphere, is notoriously unstable and prone to polymerisation. Therefore, to safely study it, researchers at ANSTO’s Australian Centre for Neutron Scattering (ACNS) developed an advanced gas delivery system for neutron diffraction experiments. This innovative system enabled researchers to securely handle diacetylene and accurately deliver it without premature reactions, establishing a foundation for future studies on the formation of co-crystals involving highly flammable, toxic, and reactive molecules at Titan-relevant temperatures (-180°C). A major challenge with diacetylene is its tendency to polymerize upon contact with oxygen, forming unstable and potentially explosive materials. One of the most significant improvements introduced by this new gas delivery system is its ability to minimize that risk—while handling diacetylene still requires caution, the system offers far greater control and safety, drastically reducing the likelihood of hazardous reactions.

Using the WOMBAT powder diffractometer at ACNS, along with X-ray diffraction (University of Sydney) and Raman spectroscopy (Jet Propulsion Laboratory, Caltech), the team determined the crystal structure of pure diacetylene under Titan-like cryogenic conditions.

After characterising diacetylene in isolation, the team started a new series of experiments to investigate its interactions when combined with pyridine. The results revealed the formation of a new crystalline phase. This newly identified solid crystal structure corroborates earlier infrared spectroscopic data. It may represent a novel class of co-crystal pertinent to Titan’s chemistry, suggesting that, if such co-crystals exist on Titan, they could influence the storage, preservation, or synthesis of complex organic molecules in its environment.

Unexpected behaviour with ethane and acrylonitrile

In addition to studying pyridine mixed with acetylene and diacetylene, Larissa and her collaborators also investigated what happens when pyridine is combined with ethane and acrylonitrile.

Surprisingly, instead of forming co-crystals, these combinations triggered a phase transition in pyridine, a change in its physical state or structure. This unexpected behaviour adds complexity to the understanding of Titan-like chemical systems and highlights the diverse ways organic molecules may interact in such extreme environments.

Looking ahead: Titan’s chemistry and the ongoing search for the origins of life

Together, Larissa and the team’s findings not only deepen our understanding of Titan’s unique environment but also shed light on the broader question of whether life could have started elsewhere in the solar system.

Pyridine-based mixed ices show promise to form the building blocks of life, such as nucleobase precursors and other key organic molecules. On the other hand, the stability of co-crystals in Titan’s harsh conditions suggests they could protect organic compounds for long periods, potentially allowing them to be transported to places where prebiotic chemistry could take place.

This research is especially relevant for upcoming missions like NASA’s Dragonfly, which prepare to explore Titan’s surface investigating its chemical and astrobiological potential for life. 

AINSE are proud to spotlight Larissa for her stellar work!

If you, like Larissa, are curious about studying the chemistry of our solar system, visit ainse.edu.au/scholarships to see how AINSE can support you.

Join us on your next stop for this lunar journey as we spotlight Jay Archer’s groundbreaking research on the effects of lunar space radiation.

While you wait, read some more out of this world research, at ainse.edu.au/research-spotlights/ and explore the rest of our catalogue.

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By Georgia Barrington-Smith

Amidst the ongoing global energy crisis, industries such as power, manufacturing, and transportation are significant contributors to energy consumption. These sectors produce substantial amounts of unwanted heat as a byproduct, typically released into the environment through exhaust systems, heated surfaces, or cooling mechanisms. This thermal energy, often considered waste, represents a largely underutilised resource.

Fortunately, innovative technologies are emerging to capture and transform this excess heat into usable energy. By harnessing this thermal energy, industries can reduce their overall energy consumption and hence lower their consumption of fossil fuels.

Advancing energy efficiency through breakthrough materials

Thermoelectric materials are a promising technology for capturing this wasted heat. These materials convert heat into electrical energy through the Seebeck effect, in which temperature differences cause the movement of charge carriers.

Recent advancements have shown that incorporating magnetic nanoparticles into these thermoelectric materials can significantly enhance their performance and energy efficiency.

Kyle Portwin, an AINSE PGRA scholar, along with collaborators at ANSTO and the University of Wollongong, has investigated the interactions between magnetic nanoparticles and tin selenide, a promising thermoelectric material, to assist in the development of higher performing energy-efficient materials.

Inside magnetic thermoelectric materials

Magnetic thermoelectric materials are highly complex systems due to the interplay of three types of (quasi)particles:

• Electrons, which carry electric charge,
• Phonons, the vibrations of the atomic lattice that transport heat, and
• Magnons, related to the spin structure of electrons.

Electrons interact with both phonons and magnons, while phonons and magnons can also influence each other independently. Understanding these interactions is crucial for designing advanced thermoelectric materials with enhanced energy efficiency.

To study these interactions, Kyle used inelastic neutron scattering (INS) techniques at ANSTO’s Australian Centre for Neutron Scattering (ACNS) facility, and computational techniques such as density functional theory (DFT), molecular dynamics and linear spin wave theory, to model the dynamics of electrons, atoms and spins in materials.

Specifically, Kyle used Time-of-Flight inelastic neutron scattering, a technique that allows the observer to “see” how particles like phonons and magnons behave inside a material, providing information about its thermoelectric performance.

Using this technique, Kyle was able to analyse some key properties of thermoelectric materials, including quasiparticle broadening (the spread of particle energy), softening (a reduction in energy), and group velocity (the speed at which disturbances travel through the material), to gain deeper insights into the microscopic interactions that govern thermoelectric efficiency.

Why are these properties important?

Understanding thermoelectric materials using inelastic neutron scattering

Kyle focused his research on one particular thermoelectric material: tin selenide (SnSe), known for its exceptional thermoelectric performance due to its ultralow thermal conductivity, and moderate electrical conductivity.

Using Time-of-Flight INS and DFT calculations, Kyle investigated how SnSe behaves when heated from 100 K – 500 K. The analysis revealed significant broadening of phonon modes, where the vibrations within the material become less well-defined. Normally, phonons have a sharp, clear energy signature, similar to a well-tuned musical note. However, broadening causes this energy range to become fuzzy, like a musical note that’s blurred by nearby vibrations, losing its sharpness and clarity. Additionally, a softening effect was observed where phonon modes shifted to lower energies. This indicating that atomic bonds had become weaker, and the system’s vibrations more anharmonic.  

As optical modes broadened and softened to lower energies, the acoustic modes became confined to a smaller region of phase space. This caused the vibrations in the material to lose energy and spread out, leading to a decrease in phonon group velocity. Consequently, the speed at which heat travels through the material slowed down. Since these vibrations typically carry heat, their limited movement reduces heat conduction through SnSe, greatly improving thermoelectric performance.

Using magnetic nanoparticles to boost thermoelectric materials

Magnetite (Fe₃O₄) nanoparticles are promising candidates for integration with thermoelectric materials because they are strongly magnetic (high magnetic moment), retain their magnetism well (high coercivity), and remain magnetic even at elevated temperatures (high Curie temperature)—a crucial feature for thermal energy applications.

When these nanoparticles become sufficiently small, they enter a special state called superparamagnetism, where each tiny particle acts like a miniature magnet that can easily flip its direction. This unique behaviour can influence how heat and electricity move through a material, potentially improving its energy performance.

To explore how magnetic nanoparticles affect thermoelectric materials, Kyle embedded Fe₃O₄ nanoparticles into a SnSe matrix. Using Time-of-Flight INS, he discovered that the vibrations in the SnSe became significantly broader—especially at higher energy levels—when combined with Fe₃O₄. This effect went beyond a simple combination of the two materials’ behaviours, indicating the possible formation of new, hybrid phonon-magnon modes inside the composite material.

These hybrid modes may influence both electrical conductivity and thermal transport by introducing new pathways for energy transfer, an area that will be further explored in the final stages of Kyle’s PhD research.

Kyle’s research lights the way for next-gen energy conversion technologies

By merging magnetism with thermoelectric materials, Kyle’s research points to a bold new direction for turning waste heat into usable energy.

Kyle’s ongoing research into the interactions of electrons, phonons, and magnons seeks to inform the development of advanced materials for improved energy conversion and long-term sustainability. Such advancements have important applications in sustainable power generation and electronic cooling.

AINSE are proud to spotlight Kyle for his pioneering work!

If you, like Kyle, want to become part of the next generation of researchers addressing global energy challenges, learn how AINSE scholarships can support your research journey at ainse.edu.au/scholarships.

To keep exploring AINSE’s research spotlights head to ainse.edu.au/research-spotlights/.

As we end Magnetic May charged up on curiosity, we transition into a new month exploring the wonders of space for Lunar June!

Keep connected as we share our first spotlight showcasing the fascinating work of Larissa Lopes Cavalcante, an AINSE PGRA scholar, examining the chemical complexity of Titan, Saturn’s largest moon!

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