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Exciton dephasing in lead sulfide quantum dots by X-point phonons

Masia, Francesco ORCID:, Langbein, Wolfgang Werner ORCID:, Moreels, Iwan, Hens, Zeger and Borri, Paola ORCID: 2011. Exciton dephasing in lead sulfide quantum dots by X-point phonons. Physical Review B 83 (20) , 201309. 10.1103/PhysRevB.83.201309

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Using a sensitive transient four-wave mixing technique in heterodyne detection, we measured the ground-state excitonic dephasing in PbS colloidal quantum dots of 4–6-nm diameter in the temperature range from 5 to 100 K. We observe an ultrafast (<100 fs) initial decay followed by a component of about 300 fs at 5 K, which becomes faster with decreasing dot size and increasing temperature. This dynamics is attributed to pure dephasing of phonon-assisted transitions in the peculiar band structure of PbS, which allows coupling to phonons with wave vectors both near the Brillouin zone center and near the (100) zone edge, the X point. We estimate an upper limit of 7% for the weight of the zero-phonon line with 2.6-ps spin-flip limited dephasing.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Physics and Astronomy
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Additional Information: 4 pp.
Publisher: American Physical Society
ISSN: 1098-0121
Funders: EPSRC
Last Modified: 05 Nov 2022 15:18

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