Dielectric and Lattice Vibrational Spectra of Cu2O Hollow Spheres in the Range of 1–10 THz

The transmitted spectra of Cu2O hollow spheres have been measured in the range of 1–10 THz and analyzed by the classical dispersion theory and group theoretical analysis. Two strong phonon resonances are observed at v1 = 4.54 THz (148.3 cm–1) and v2 = 4.91 THz (163.5 cm–1), corresponding to the transverse optical (TO) phonon and longitudinal optical (LO) phonon modes, respectively. In addition, we have identified a possible surface optical (SO) phonon mode located between the TO and LO phonon frequencies and have observed that a forbidden phonon mode at 9.36 THz (312 cm–1) is activated due to the imperfect lattice of the Cu2O hollow spheres. The optical and dielectric parameters are also derived and discussed based on the Lorentz model of dielectric response.