• Open Access

Spin-Flip Limited Exciton Dephasing in CdSe/ZnS Colloidal Quantum Dots

Francesco Masia, Nicolò Accanto, Wolfgang Langbein, and Paola Borri
Phys. Rev. Lett. 108, 087401 – Published 22 February 2012

Abstract

The dephasing time of the lowest bright exciton in CdSe/ZnS wurtzite quantum dots is measured from 5 to 170 K and compared with density dynamics within the exciton fine structure using a sensitive three-beam four-wave-mixing technique unaffected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing of 109 ps at 5 K, much faster than the 10ns exciton radiative lifetime. The zero-phonon line dephasing is explained by phonon-assisted spin flip from the lowest bright state to dark-exciton states. This is confirmed by the temperature dependence of the exciton lifetime and by direct measurements of the bright-dark–exciton relaxation. Our results give an unambiguous evidence of the physical origin of the exciton dephasing in these nanocrystals.

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  • Received 27 July 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.087401

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

© 2012 American Physical Society

Authors & Affiliations

Francesco Masia, Nicolò Accanto, Wolfgang Langbein, and Paola Borri

  • Cardiff University School of Physics and Astronomy and School of Biosciences, The Parade, Cardiff CF24 3AA, United Kingdom

Comments & Replies

Comment on “Spin-Flip Limited Exciton Dephasing in CdSe/ZnS Colloidal Quantum Dots”

Mark J. Fernée, Yann Louyer, Philippe Tamarat, and Brahim Lounis
Phys. Rev. Lett. 109, 229701 (2012)

Masia et al. Reply:

Francesco Masia, Nicolò Accanto, Wolfgang Langbein, and Paola Borri
Phys. Rev. Lett. 109, 229702 (2012)

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Issue

Vol. 108, Iss. 8 — 24 February 2012

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