Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated raman spectroscopy

Daniel C. Hannah; Kristen E. Brown; Ryan M. Young; Michael R. Wasielewski; George C. Schatz; Dick T. Co; Richard D. Schaller

doi:10.1103/PhysRevLett.111.107401

Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated raman spectroscopy

Daniel C. Hannah^*, Kristen E. Brown, Ryan M. Young, Michael R. Wasielewski, George C. Schatz, Dick T. Co, Richard D. Schaller

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

We report femtosecond stimulated Raman spectroscopy measurements of lattice dynamics in semiconductor nanocrystals and characterize longitudinal optical (LO) phonon production during confinement-enhanced, ultrafast intraband relaxation. Stimulated Raman signals from unexcited CdSe nanocrystals produce a spectral shape similar to spontaneous Raman signals. Upon photoexcitation, stimulated Raman amplitude decreases owing to experimentally resolved ultrafast phonon generation rates within the lattice. We find a ∼600 fs, particle-size-independent depletion time attributed to hole cooling, evidence of LO-to-acoustic down-conversion, and LO phonon mode softening.

Original language	English (US)
Article number	107401
Journal	Physical Review Letters
Volume	111
Issue number	10
DOIs	https://doi.org/10.1103/PhysRevLett.111.107401
State	Published - Sep 5 2013

ASJC Scopus subject areas

Physics and Astronomy(all)

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10.1103/PhysRevLett.111.107401

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title = "Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated raman spectroscopy",

abstract = "We report femtosecond stimulated Raman spectroscopy measurements of lattice dynamics in semiconductor nanocrystals and characterize longitudinal optical (LO) phonon production during confinement-enhanced, ultrafast intraband relaxation. Stimulated Raman signals from unexcited CdSe nanocrystals produce a spectral shape similar to spontaneous Raman signals. Upon photoexcitation, stimulated Raman amplitude decreases owing to experimentally resolved ultrafast phonon generation rates within the lattice. We find a ∼600 fs, particle-size-independent depletion time attributed to hole cooling, evidence of LO-to-acoustic down-conversion, and LO phonon mode softening.",

author = "Hannah, {Daniel C.} and Brown, {Kristen E.} and Young, {Ryan M.} and Wasielewski, {Michael R.} and Schatz, {George C.} and Co, {Dick T.} and Schaller, {Richard D.}",

year = "2013",

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doi = "10.1103/PhysRevLett.111.107401",

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T1 - Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated raman spectroscopy

AU - Hannah, Daniel C.

AU - Brown, Kristen E.

AU - Young, Ryan M.

AU - Wasielewski, Michael R.

AU - Schatz, George C.

AU - Co, Dick T.

AU - Schaller, Richard D.

PY - 2013/9/5

Y1 - 2013/9/5

N2 - We report femtosecond stimulated Raman spectroscopy measurements of lattice dynamics in semiconductor nanocrystals and characterize longitudinal optical (LO) phonon production during confinement-enhanced, ultrafast intraband relaxation. Stimulated Raman signals from unexcited CdSe nanocrystals produce a spectral shape similar to spontaneous Raman signals. Upon photoexcitation, stimulated Raman amplitude decreases owing to experimentally resolved ultrafast phonon generation rates within the lattice. We find a ∼600 fs, particle-size-independent depletion time attributed to hole cooling, evidence of LO-to-acoustic down-conversion, and LO phonon mode softening.

AB - We report femtosecond stimulated Raman spectroscopy measurements of lattice dynamics in semiconductor nanocrystals and characterize longitudinal optical (LO) phonon production during confinement-enhanced, ultrafast intraband relaxation. Stimulated Raman signals from unexcited CdSe nanocrystals produce a spectral shape similar to spontaneous Raman signals. Upon photoexcitation, stimulated Raman amplitude decreases owing to experimentally resolved ultrafast phonon generation rates within the lattice. We find a ∼600 fs, particle-size-independent depletion time attributed to hole cooling, evidence of LO-to-acoustic down-conversion, and LO phonon mode softening.

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JO - Physical Review Letters

JF - Physical Review Letters

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Direct measurement of lattice dynamics and optical phonon excitation in semiconductor nanocrystals using femtosecond stimulated raman spectroscopy

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