Acoustic Phonon Contributions to the Emission Spectrum of Single CdSe Nanocrystals

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• 作者：Mark J. Fern&eacute ; e ; Brad N. Littleton ; Steven Cooper ; Halina Rubinsztein-Dunlop ; Daniel E. Gó ; mez ; Paul Mulvaney
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 14, 2008
• 年：2008
• 卷：112
• 期：6
• 页码：1878 - 1884
• 全文大小：408K
• 年卷期：v.112,no.6(February 14, 2008)
• ISSN：1932-7455

文摘

Narrow zero-phonon emission lines are observed in single CdSe/CdZnS core/shell colloidal nanocrystals overa range of cryogenic temperatures up to 40 K. These nanocrystals display dramaticaly improved spectralstability enabling the observation of acoustic phonon sidebands accompanying most zero-phonon lines. Adiscrete phonon mode is attributed to the electron coupling to the l = 0 acoustic breathing mode via thedeformation coupling. The Huang-Rhys parameter, S_ac, for this interaction is found to vary from 0.0016 to0.09, demonstrating a wide dispersion in exciton-phonon coupling between different nanocrystals. Indeed,we observe single nanocrystals in which all acoustic phonon sidebands vanish, in close agreement withtheoretical predictions that there should be negligible acoustic phonon coupling in an ideal spherical CdSenanocrystal. Such nanocrystals are virtually decoupled from their environment, which is potentially usefulfor quantum technologies, such as single photon sources and quantum computing. In general, the ability todetect and quantify phonon interactions within single nanocrystals will provide significant insight into energyrelaxation and dephasing processes in these systems.