When a liquid is heated, the molecules inside it begin to move about and jump around. As the temperature increases, particles start to move more frequently and cover increasingly larger distances. Together, these movements make various examples of molecular dances known as collective excitations.
Now, a new study has uncovered a link between the microscopic movements of particles in a liquid and its ability to absorb heat.
The study was conducted by scientists from the Queen Mary University of London, Bauman Moscow State Technical University, and the Institute for High-Pressure Physics RAS in Russia.
Scientists used computer simulations to model the molecular behaviors of liquids. They found that the collective excitations observed in liquids can eventually become so intense that they start to interact with each other, changing how the liquid itself takes up the heat.
This new relationship’s disclosure overcomes any barrier between liquids’ microscopic behavior and their fundamental perceptible property—heat capacity. It likewise proposes an ideal temperature region for cooling applications, and it is conceivable to control this region by tuning the pattern of molecular “dances.”
Professor Stanislav Yurchenko, Professor at Bauman Moscow State Technical University and author of the study, said: “We hope to uncover this connection between collective excitations and heat absorption, could provide a path towards the general theory of liquids, which is one of the longest-standing challenges in condensed matter physics.”
Dr. Andrei Sapelkin, the senior lecturer in the School of Physics and Astronomy at Queen Mary, added: “Despite being all around us, liquids remain one of the least understood states of matter. So much so that, unlike in cases of solids and gasses, there is no general microscopic theory of liquids that extends from the atomic or molecular interactions within a liquid to the macroscopic level. With this discovery, we hope to bridge this gap.”
- Nikita P. Kryuchkov et al. Universal Effect of Excitation Dispersion on the Heat Capacity and the Gapped States in Fluids, Physical Review Letters (2020). DOI: 10.1103/PhysRevLett.125.125501