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 journalArticlepeer-review

21 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 languageEnglish (US)
Article number107401
JournalPhysical Review Letters
Volume111
Issue number10
DOIs
StatePublished - Sep 5 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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