Masia, Francesco  ORCID: https://orcid.org/0000-0003-4958-410X, Accanto, Nicolo, Langbein, Wolfgang Werner ORCID: https://orcid.org/0000-0001-9786-1023 and Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314
2012.
Spin-flip limited exciton dephasing in CdSe/ZnS colloidal quantum dots.
Physical Review Letters
108
(8)
, 087401.
10.1103/PhysRevLett.108.087401
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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 ∼10 ns 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.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Biosciences Schools > Physics and Astronomy |
| Subjects: | Q Science > Q Science (General) Q Science > QC Physics |
| Publisher: | American Physical Society |
| ISSN: | 0031-9007 |
| Funders: | EPSRC |
| Last Modified: | 17 May 2023 21:12 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/33619 |
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