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.
Highlights
Nano materials have attracted great research and industrial interest in recent years because of their unique chemical, physical, optical, electrical and transport properties [1, 2]
In this paper we report density functional theory (DFT)‐based Raman spectroscopy to study the vibrational modes of hydrogenated CdS‐NPs with (CdS) NPs sized around one nanometre
The high frequency Raman modes observed at a frequency of 1562 cm‐1 and 2789 cm‐1 for 2 atom CdS‐NPs are Cd‐H anti‐symmetric stretching S‐H anti‐symmetric stretching modes respectively as per the Amsterdam density functional (ADF) library and the literature
Summary
Nano materials have attracted great research and industrial interest in recent years because of their unique chemical, physical, optical, electrical and transport properties [1, 2]. Nabani,oAtebcdhunl oSlh.,a2k0o1o2r ,aVndol.N2a,jmAurtl.H7a:2ss0a1n2: 1 A Density Functional Theory Study of Raman Modes of Hydrogenated Cadmium Sulphide Nanoparticles applications in electronic and photonic devices [7,8,9,10]. The functionality of these devices has strong correlation with the electronic and structural properties of the material used. The structures of NPs can be stabilized electrostatically by attaching ligand with a negatively charged end group, thereby introducing repulsive force between the particles to keep them separated For this purpose hydrogen may be used because it has an ambivalent nature. In this paper we report DFT‐based Raman spectroscopy to study the vibrational modes of hydrogenated CdS NPs sized around one nanometre
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