Raman Scattering Study of Cu3SnS4 Colloidal Nanocrystals

We report the results of a Raman spectroscopy study of lattice vibrations in colloidal Cu(3)SnS4 nanocrystals (NCs) in a broad spectral range between 70 and 1200 cm1. The crystallographic structure and lattice symmetry of NCs is confirmed by the X-ray diffraction data. The three most intensive Raman features in the spectra obtained in this work coincide with those previously reported for thin films of orthorhombic Cu3SnS4. Rather small scattering line widths indicate high structural perfection of the NCs. Along with the known modes of Cu3SnS4, several additional phonon peaks are observed for this compound in the frequency ranges not studied earlier, below 200 and between 500 and 1200 cm1. All experimentally determined Raman bands are found to correlate well with the results of ab initio calculations of phonon frequencies in Cu3SnS4 of the orthorhombic modification (space group #31, Pmn2(1)).