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

Masia, Francesco ORCID: https://orcid.org/0000-0003-4958-410X, Langbein, Wolfgang Werner ORCID: https://orcid.org/0000-0001-9786-1023, Moreels, Iwan, Hens, Zeger and Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314 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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Abstract

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:	15 May 2023 23:28
URI:	https://orca.cardiff.ac.uk/id/eprint/22819

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