Al2O3 NPs synthesised by laser ablation in liquids: Plasma temperatures and chemical composition

What is it about?

In the framework of the synthesis of gamma-Al2O3 nanoparticles by PLAL in water environment, we report the time-resolved spectroscopy of the Al and AlO species. From the electron density, the rotational and vibrational temperatures of the AlO molecules, we demonstrate that after 2µs the plasma turns into a hot neutral gas of 3400 K. The quick oxidation of the Al atoms leading to AlO molecules is in good agreement with the DFT calculation of Patzer et al. The same theoretical study shows that only small molecules are stable when the temperature is higher than 3000 K. We can thus state that nucleation cannot take place before a few microseconds.

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Photo by Aron Visuals on Unsplash

Photo by Aron Visuals on Unsplash

Why is it important?

From the measurement of the density ratio Al/AlO, we succeed to derive the relative chemical composition in the plasma. The article reports one of the first measurement of the rotational temperature of diatomic molecules in the framework of a laser generated plasma in water.

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