Characterising nanoparticles by lattice vibration frequency

In this study, we simulate that irradiation of nanoceria has potential inducing (breathing mode) lattice vibrations. Irradiation therefore has potential to be used in increasing the catalytic activity of nanoceria structures. If irradiation can be implemented to vibrate atoms off their lattice sites, in a similar manner to temperature, this would enable surface atoms to be more easily extracted. Extracted surface oxygen has potential uses in oxidative catalysis or to modulate oxygen concentration in biological environments with nanoceria as a nanozyme. Here, Molecular Dynamics (MD) simulation was used to calculate vibration (breathing mode) frequencies of various ceria nanoparticles. Vibration was induced in polyhedral nanoparticles, 665 - 6708 cerium atoms in size, and compared to the vibrations induced in nanocylinders comprising 653 - 6721 cerium atoms. The simulations revealed that breathing mode frequencies decrease with increasing size for both polyhedral

and cylindrical nanoparticles in accord with experiment. The simulations also revealed that breathing mode frequencies depend upon the aspect ratio of nanocylinders. The simulations suggest that breathing mode vibrational spectra can be used as a fingerprint to identify the size, shape, and aspect ratio distribution of a ceria nanomaterial sample.