One-phonon Raman scattering from arrays of semiconductor nano-crystals

Vasilevskiy, Mikhail; Rolo, Anabela G.; Gomes, M. J. M.

doi:10.1016/s0038-1098(97)00356-6

Cited by 30 publications

(27 citation statements)

References 20 publications

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“…The second step is to calculate the relative contributions of these modes with different n to Raman spectra, and that depends on whether the excitation energy is in resonance with some particular electronhole state (the Fröhlich mechanism of the electron-phonon interaction is the most efficient) or whether it is off-resonance [4].…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Raman spectroscopy of CdS nanoparticles

Kostić

Romčević

2004

phys. stat. sol. (c)

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PACS 63.22.+m, 78.30.Fs, 78.67.Hc CdS nanoparticles with average radius R o = 2.2 nm have been investigated by Raman scattering measurements. The nanoparticles, synthesized using aqueous solution precipitation, are small enough to show effects due to confinement. In the Raman spectra of CdS nanoparticles an asymmetric Raman line was observed. The dominant line was at about 300 cm -1 having asymmetric broadening for ω < 300 cm -1 . We considered a single crystalline sphere to calculate the relative contributions of the confined modes to the Raman scattering. The second harmonic of these confined modes was also registered.1 Introduction Unique properties (conductivity, diffusion, reactivity, sintering, etc) have been reported for nanostructured materials, all of which result from the interfacial characteristics. Also, nanosized particles of various direct-gap semiconductors exhibit unusual optical properties, which make them attractive as materials for nonlinear optical elements and luminescent devices. Because of the quantum confinement of the electronic states, diluted magnetic semiconductor nanostructures have great potential for applications. Vibrational spectroscopy (far-infrared and Raman) is a powerful, non-destructive procedure sensitive to local environment, ideal for in site probing during growth, and during device fabrication and operation [1].Like in the bulk materials, far-infrared spectroscopy provides information about optical vibrational modes, complementary to that obtained from Raman spectra. The Raman spectroscopy is now a standard tool for the study of semiconductor nanoparticles [2][3][4][5][6]. In this paper we report the results of our experimental and theoretical studies of the Raman active vibrations in nanosized CdS crystal. We deal with the effects of phonon mode confinement noticeable in our samples.

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Section: Synthesis and Characterizationmentioning

confidence: 99%

Raman spectroscopy of CdS nanoparticles

Kostić

Romčević

2004

phys. stat. sol. (c)

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“…The functionality of these devices has strong correlation with the electronic and structural properties of the material used. These properties depend upon the vibrational characteristics of the materials which are in turn related to the size of NPs and can be best explored using infrared and Raman scattering techniques [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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

Majid

Ahmad

Nabi

et al. 2012

Nanomaterials and Nanotechnology

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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.

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“…1, were relaxed by geometry optimization to attain a stable structure with minimized energy. In the calculations we used the core shell and valence shell for Cd: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 and 5s 2 , 4d 10 . Similarly, for S: 1s 2 2s 2 2p 6 and 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 and for Sc: 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 core states and 4s 2 , 3d 1 valence states, respectively.…”

Section: Computational Detailsmentioning

confidence: 99%

“…2 and the corresponding HOMO-LUMO are shown in enlarged view boxes. The lower energy active AO's 4d 10 and 3s 2 of Cd and S, respectively, combine to form filled restricted bonding σ and anti-bonding σ* MO's. The restricting trait accounts for two electrons with opposite spins (↑↓) that can be accommodated in the same molecular orbital, according to Pauli exclusion principle.…”

Section: Electronic Propertiesmentioning

confidence: 99%

“…The functionality of these devices has strong correlation with the electronic and structural properties of the material used. These * E-mail: najamalhassan@yahoo.com properties depend upon the vibrational characteristics of the materials which are, in turn, related to the size of nanoparticles and can be best explored using infrared and Raman scattering techniques [8][9][10]. II -VI semiconductor nanoparticles have proven to fulfill this requirement to large extent.…”

Section: Introductionmentioning

confidence: 99%

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

Réhman

Majid

Hassan

et al. 2015

Materials Science-Poland

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In the present work a systematic study was carried out to understand the influence of Sc doping on electronic and optical properties of CdS nanoparticles. The geometry optimization and symmetry computation for CdS and Sc doped CdS nanoparticles using Density Functional Theory (DFT) on B3LYP level with the QZ4P for Cd and DZ2P for sulphur and Sc were performed by Amsterdam Density Functional (ADF). The results show that HOMO-LUMO gap as well as electronic and optical properties of CdS clusters vary with Sc doping. The HOMO-LUMO gap is affected by the dopant and its value decreases to 0.6 eV. Through considering the numerical integration scheme in the ADF package, we investigated different vibrational modes and our calculated Raman and IR spectra are consistent with the reported result. The calculated IR and Raman peaks of CdS and Sc doped CdS clusters were in the range of 100 to 289 cm −1 , 60 cm −1 to 350 cm −1 and 99 cm −1 to 282 cm −1 , 60 cm −1 to 350 cm −1 , respectively, which was also confirmed by experiment as well as a blue shift occurrence. Subsequently, for deeper research of pure and doped CdS clusters, their absorption spectra were calculated using time-dependent DFT method.

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One-phonon Raman scattering from arrays of semiconductor nano-crystals

Cited by 30 publications

References 20 publications

Raman spectroscopy of CdS nanoparticles

Raman spectroscopy of CdS nanoparticles

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

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

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