International Journal of Thermophysics (2018) 39:110 https://doi.org/10.1007/s10765-018-2428-6 ICPPP 19 Photoacoustic Spectroscopy Investigation of Zinc Oxide/Diatom Frustules Hybrid Powders F. R. Lamastra 1 · M. L. Grilli 2 · G. Leahu 3 · A. Belardini 3 · R. Li Voti 3 · C. Sibilia 3 · D. Salvatori 4 · I. Cacciotti 5 · F. Nanni 1,4 Received: 1 November 2017 / Accepted: 4 August 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Photoacoustic spectroscopy investigation was carried out on ZnO nanoparticles grown at 80 °C on porous surface of diatomite (DE) by sol–gel technique, using zinc acetate dihydrate as ceramic precursor and triethanolamine to mediate the surface growth of the nanoparticles. Absorption and scattering characteristics of hybrid ZnO/DE powder in the UV–Vis range were inferred by photoacoustic spectroscopy, and results were analyzed based on Helander’s theory. In particular, we discussed in detail the proce- dure to calculate the absorption and scattering spectra of the hybrid powder showing how from the scattering coefficient in the 300–450 nm range it is possible to obtain information on the size distribution of the ZnO nanospheres. By applying photoacous- tic spectroscopy for different modulation frequencies, we showed that is also possible to perform a size distribution depth profile of the ZnO aggregates, opening the way to interesting developments in this research field. Keywords Diatomite · Light absorption · Light scattering · Photoacoustics · Sol–gel synthesis · Spectroscopy · Zinc oxide nanoparticles This article is part of the selected papers presented at the 19th International Conference on Photoacoustic and Photothermal Phenomena. B R. Li Voti roberto.livoti@uniroma1.it 1 Italian Interuniversity Consortium on Materials Science and Technology (INSTM), Research Unit Roma Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy 2 ENEA, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome, Italy 3 Department of Fundamental and Applied Science for Engineering, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Rome, Italy 4 Department of Enterprise Engineering, University of Rome ‘Tor Vergata’, Via del Politecnico 1, 00133 Rome, Italy 5 Department of Engineering, University of Rome Niccolò Cusano, Via Don Carlo Gnocchi 3, 00166 Rome, Italy 0123456789().: V,-vol 123