Laser power influence on Raman spectra of ZnO(Co) nanoparticles

• ZnO doped with CoO, samples prepared by calcination method.
• Influence of laser power densities on Co3O4 and ZnO Raman spectroscopy investigated.
• Redshift and broadening of peaks with increase of laser power density.
• Changes in relative peaks intensity and formation of cobalt dimers are induced.

Influence of laser power on nanocrystalline samples of ZnO(Co) prepared by commonly used wet chemistry method followed by calcination was investigated. Previous confirmation of the existence of ZnO and Co3O4 phases was based on the X-ray diffraction measurements. Here we report the experimental spectra of non-resonant Raman scattering in the range between 100 cm−1 and 1600 cm–1, for a series of samples irradiated with four different laser power densities. The laser power density has different influence on relative intensity of peaks that belong to ZnO phase than on those corresponding to Co3O4 phase. Both peak types show characteristic broadening and red shift toward lower frequencies. The laser power densities used in our study did not cause thermal destruction in any of the investigated samples. Laser-induced local heating effects in samples caused formation of cobalt dimers on the surface of Co3O4.

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