Apart from the three main vibration modes above, Wang et al. You reported a multiphonon band of CuO nanostructures, which appears at a wavenumber of 1130 cm−1 and relates to the inharmonic coupling between phonons in polar solids. In particular, the multiphonon band in CuO was suggested to be the stretching vibration in the – plane induced by the electronic density variation in this layer. The intensity of the multiphonon Raman peak is much weaker than that of the one-phonon band and varies with morphology and the size of the as-prepared CuO nanostructures. The authors reported that the multiphonon band of the as-prepared CuO nanostructures with belt-like morphology possesses higher intensity than that of the CuO nanostructures with shuttle-like morphology.
In comparison, the Raman intensity of the multiphonon band of the shuttle-like morphology is higher than that of the CuO nanostructures with bamboo leaf-like morphology. The anisotropy of different nanostructures explained the difference in the Raman intensity of varying morphology. The electronic movement along the – plane becomes significant in-plane and promotes the power of 2Bg mode in the belt-, shuttle-, and bamboo leaf-like nanostructures. Another explanation for the variation in the Raman intensity of this mode is the phonon-plasmon coupling due to the high local density of anisotropic carriers in CuO nanostructures. The variation in the multiphonon intensity shows a finite size and crystallinity effect of CuO nanostructures. For nanomaterials, several methods could be applied to characterize the optical properties or estimate the bandgap. Among these methods, UV-vis absorption spectroscopy, a nondestructive and quick technique, is one of the most convenient methods to reveal semiconducting materials' energy structures and optical properties. If you are looking for high quality, high purity, and cost-effective copper oxide, or if you require the latest price, please email contact mis-asia.
