Resonance Raman studies of the ground and lowest electronic excited state in CdS nanocrystals

Shiang, J. J.; Risbud, S. H.; Alivisatos, A. Paul

doi:10.1063/1.464501

Cited by 246 publications

(229 citation statements)

References 42 publications

Supporting

Mentioning

207

Contrasting

Order By: Relevance

“…24 An increase of the strength of carrier-phonon coupling with increasing carrier confinement was observed in Cd͑SSe͒ nanocrystals, 25 while an opposite trend was shown for CdTebased quantum wells 26 and CdS QDs. 27 Our data indicate that the strength of carrier-phonon coupling, ␥, is larger for dots with the higher emission energies ͑Ͼ1 eV at RT͒ and smaller size ͑d Ͻ 7 nm͒ ͓see Fig. 3͑b͔͒ in qualitative agreement with theory.…”

supporting

confidence: 75%

Temperature dependence of the photoluminescence emission from thiol-capped PbS quantum dots

Turyanska

Patanè

Henini

et al. 2007

Applied Physics Letters

100

View full text Add to dashboard Cite

The authors report the temperature dependence of the near-infrared photoluminescence ͑PL͒ emission from thiol-capped PbS quantum dots. The high thermal stability of the PL allows the authors to study the thermal broadening of the dot emission over an extended temperature range ͑4 -300 K͒. The authors show that the linewidth of the dot PL emission is strongly enhanced at temperatures above 150 K. This behavior is attributed to dephasing of the quantum electronic states by carrier interaction with longitudinal optical phonons. The authors' data also indicate that the strength of the carrier-phonon coupling is larger in smaller dots. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2711529͔ Semiconductor nanocrystals, also known as quantum dots ͑QDs͒, are artificial nanostructures with energy spectra and electronic wave functions similar to those observed in atomic physics. 1 In the last two decades, they have been synthesized using different techniques ͑electron-beam lithography, epitaxy, and colloidal chemistry͒ and a number of different semiconductor materials. They have been studied in optical and transport experiments and have also formed the basis for devices of potential interest for quantum information processing, 2 spintronics, 3 optoelectronics, 4,5 and optical imaging in biological studies. 6 Of the various nanocrystals, PbS-based QDs have emerged as promising candidates for optical applications in the near-infrared region of the electromagnetic spectrum. 5,[7][8][9] In particular, since the emission wavelength of PbS dots can be controlled and tailored within the spectroscopic window of 1.0-1.2 m of low absorption of biological systems, water soluble PbS nanocrystals have the potential to be used as biocompatible fluorescent labels and to replace traditional organic fluorescent dyes.The effect of temperature T on the optical properties of PbS quantum dots is of great importance for their use in room temperature ͑RT͒ applications. Recently, an unusually large linewidth ͑ϳ100 meV͒ for the RT photoluminescence ͑PL͒ emission from an individual PbS QD was reported. 10 However, the effect of temperature on the spectral linewidth of either the emission from an individual or an ensemble of PbS dots is still largely unknown. In this work, we study the PL properties of thiol-capped PbS QDs with emission wavelengths tunable from 1.1 to 1.3 m. The intensity of the PL is only weakly affected by temperature, thus allowing us to study the thermal broadening of the QD emission over an extended temperature range ͑4 -300 K͒. We find that the optical linewidth W exhibits a strong increase for T Ͼ 150 K. This increase is attributed to dephasing of the quantum electronic states by carrier interaction with thermally generated longitudinal optical ͑LO͒ phonons and is shown to be enhanced in smaller dots.Our PbS QDs were prepared in aqueous solution following the method described by Bakueva et al. 11 First we prepared a 15 ml aqueous solution containing 2.5ϫ 10 −4 mol lead acetate Pb͑CH 3 COO͒ 2 and a mixture of thiols, i...

show abstract

supporting

confidence: 75%

Temperature dependence of the photoluminescence emission from thiol-capped PbS quantum dots

Turyanska

Patanè

Henini

et al. 2007

Applied Physics Letters

100

View full text Add to dashboard Cite

show abstract

“…The electric field within materials correlates to Coulomb interaction with the exciton, and the strength of electron-phonon coupling will be enhanced if the wavelength of the phonon vibration is close to the spatial extent of the exciton. [1][2][3][4][5][6][7][8][9][10][11][12][13] Recently, the fabrication of nanoparticles (NPs) and quantum dots (QDs) makes it possible to investigate the electron-phonon interaction beyond the bulk approximation. Such quantumconfined electronic systems differ completely from their bulk counterparts in the optical and electronic properties.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Resonant Raman Scattering and Electron−Phonon Coupling from Self-Assembled Secondary ZnO Nanoparticles

et al. 2005

View full text Add to dashboard Cite

Self-assembled secondary ZnO nanoparticles, recognized with the agglomeration of crystalline subcrystals, are successfully synthesized by a simple sol-gel method. TEM images display that one artificial cluster behaves in a single-crystal-like wurtzite structure because subcrystals coagulate as the same crystal orientation. Moreover, from the resonant Raman scattering, the as-grown sample exhibits phonon red shift; meanwhile, the coupling strength between electron and longitudinal optical phonon, determined by the ratio of secondto first-order Raman scattering cross sections, diminishes compared with the samples after postannealing at 350 and 500°C. The size dependence of electron-phonon coupling is principally as a result of the Fröhlich interaction.

show abstract

“…The strength of the EPC is expressed by the Huang-Rhys factor, S, given by Δ 2 /2 where Δ is the difference between the potential minima of the two electronic states along the ground-state dimensionless normal coordinate. [1][2][3][4] (With this definition, Δ = 1 when the two potential energy surfaces are displaced by /√2 where is the standard deviation of the probability distribution in the ground vibrational state, | 0 | 2 . Some workers [5][6][7][8] use an alternative definition in which Δ is smaller by √2 , and S = Δ 2 .)…”

Section: Introductionmentioning

confidence: 99%

Resonance Raman Overtone Intensities and Electron–Phonon Coupling Strengths in Semiconductor Nanocrystals

Kelley

2013

J. Phys. Chem. A

View full text Add to dashboard Cite

For linear electron-phonon coupling, the Huang-Rhys factor, S, gives the intensity ratio of the one-quantum vibronic transition (0→1) to the purely electronic origin transition (0→0) in a vibrationally resolved, zero-temperature absorption or emission spectrum. It is often assumed that the overtone to fundamental integrated intensity ratio in resonance Raman scattering of semiconductor nanocrystals is equal to or proportional to S, or that S may be determined from the overtone intensity in some other straightforward manner. In fact, this is not generally possible because of different excitation profiles for overtones and fundamentals, differential sensitivity of overtones and fundamentals to electronic dephasing, and interference effects from partially overlapping electronic transitions. Here we examine the relationship between the Huang-Rhys factor and the overtone to fundamental intensity ratio through spectroscopic simulations using parameters appropriate to II-VI semiconductor nanocrystals such as CdSe. A simple equation relating the overtone to fundamental Raman intensity ratio to the Huang-Rhys factor is obtained only in the case of a single resonant electronic state, excitation at the maximum of the inhomogeneously broadened absorption band, and a homogeneous linewidth small compared with the phonon frequency.

show abstract

Resonance Raman studies of the ground and lowest electronic excited state in CdS nanocrystals

Cited by 246 publications

References 42 publications

Temperature dependence of the photoluminescence emission from thiol-capped PbS quantum dots

Temperature dependence of the photoluminescence emission from thiol-capped PbS quantum dots

Enhanced Resonant Raman Scattering and Electron−Phonon Coupling from Self-Assembled Secondary ZnO Nanoparticles

Resonance Raman Overtone Intensities and Electron–Phonon Coupling Strengths in Semiconductor Nanocrystals

Contact Info

Product

Resources

About