Scientists use lasers to break nature’s strongest chemical bonds

Some chemical bonds can be really permanent. A way has been found to disassemble it, which may be useful to us not only in chemistry.

In the exact sciences, the formation of new chemical bonds is more desirable than the breaking of existing ones. But not always. Decay reactions are important in the context of our understanding of the laws of nature. Scientists at Lawrence Livermore National Laboratory (LLNL) obtained very accurate data on the behavior of dense nitrogen under extreme conditions, which could contribute to a better understanding of the interior of exoplanets and white dwarfs. Details are described in physical review messages.

break atomic bonds

Molecular nitrogen (N₂) is about 78% of the air we breathe. Two nitrogen atoms are linked by a triple covalent bond, the strongest of which is found in simple diatomic molecules.

Nitrogen is also a major component of celestial bodies in the outer solar system and beyond. Astronomers believe that ammonia storms (NH₃) occur on giant planets such as Jupiter, while the dwarf planet Pluto, the icy moon of Saturn Titan and the icy moon of Neptune, Triton, have nitrogen-rich atmospheres.₂.

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LLNL researchers conducted shock experiments on pre-pressed molecular nitrogen liquid at pressures up to 800 gigapascals. They observed clear signs of complete molecular dissociation near 70-100 GPa and 5-10 kK and the onset of ionization of the outer electrons above 400 GPa and 50 kK. what does it mean?

It’s exciting that we can use shock waves to break up these molecules and understand how pressure and density cause changes in chemical bonds. Studying how nitrogen molecules break down and how electrons are released is a great test of the most advanced computer simulations and theoretical modeling. Nitrogen and hydrogen are light diatomic molecules, but hydrogen atoms are so small that it is very difficult to recreate their behavior under extreme pressure and heat conditions using computer simulations.Young Jae Kim, LLNL physicist and lead author

New research resolves a puzzling contrast between previous experiments with warm dense nitrogen and predictions based on the results of density functional theory (DFT) simulations.

We have shown that the theory of density functions describes our experiments well. This is a very rigorous and useful test.Young Jae Kim

This research is part of the Laboratory Directed Research and Development (LDRD) project, which aims to develop new experimental techniques for dynamic laser compression using diamond chambers (DAC). These techniques will reveal new physical and chemical phenomena in mixtures of low atomic number, such as those rich in water, over a wide range of conditions of unprecedented pressure, temperature and density. These studies have an impact on the formation and evolution of planets and make it possible to learn about the properties of matter under extreme conditions.

There is still a lot we can learn from these types of dynamic laser compression experiments. This is a very exciting field as there are many opportunities for developing innovative measurements and understanding how matter responds to extreme conditions. This is critical for the interpretation of astronomical observations and a better understanding of the formation and evolution of celestial bodies such as white dwarfs and exoplanets.Marius Melot of LLNL and lead author of the paper