A Density Functional Theory Study of Raman Modes of Hydrogenated Cadmium Sulphide Nanoparticles

Abstract

Raman scattering investigations based on density functional theory (DFT) calculations were performed to explore the vibrational modes of wurtzite structured CdS nanoparticles (NPs). The calculations were performed to obtain the Raman spectra for the CdS containing 2, 4, 8 and 12 atoms to study the size dependence. Several vibrational modes indicating stretching and bending features related to Cd and S atoms were observed. Modifications of the frequency and intensity of different Raman modes with an increase in number of atoms in NPs are discussed in detail. It is found that the frequency of the CdS symmetric stretching mode of vibration shows a consistent red shift and that of CdS anti-symmetric stretching shows a consistent blue shift with the increase in the number of atoms. Hydrogen atoms were added in order to make the closed shell configuration and saturate the NPs as per the requisite for calculating the Raman spectra. This produced some additional modes of vibration related to hydrogen atoms. The SH stretching mode showed a consistent red shift and the CdH stretching mode showed a consistent blue shift with an increase in the number of atoms in NPs. The results generated are found to be in close agreement with the literature. The observed red shift in different modes is assigned to stimulated Raman stretching and blue shift is ascribed to the coherent anti-stokes Raman scattering.

Influence of Al doping on optical properties of CdS/PVA nanocomposites: Theory and experiment

“…Cd-S and Al-S are observed to be 2.53 and 2.25Å while Cd-S-Cd and Al-S-Cd bond angles of 109.5° and 106.5° respectively. The parameters are found to be in good agreement with other previous reports [15,16].The average distance of separation between the cluster and nearest -OH group of each chain is about 3.1Å.…”

Room Temperature Pulse Electrodeposition of CdS Thin Films for Application in Solar Cells and Photoelectrochemical Cells

“…Micro-Raman spectra of pulse electrodeposited and annealed CdS films shown in Figure 4b, reveal well-defined CdS peaks for the as-deposited and annealed films at a Raman shift of 261 cm −1 corresponding to CdS symmetric stretching mode and at 304 cm −1 assigned to longitudinal optical (LO) A 1 mode. 40 In addition, the second harmonic of the A 1 mode is observed at 608 cm −1 . Raman analysis further corroborates the XRD studies to confirm the presence of hexagonal CdS phase in as-deposited and annealed samples prepared by pulse electrodeposition.…”

A DFT study of the effects of Sc doping on electronic and optical properties of CdS nanoparticles

“…The studies of semiconductor nanoparticles have been an interesting field of research for more than two decades. This is because they give an opportunity to understand the physical properties in low dimensions and to explore their vast potential for application in, e.g., optoelectronics [3]. Over the past two decades, investigations on quantum sized semiconductor particles have increased enormously due to their novel applications in electronic and photonic devices [4][5][6][7].…”