Understanding the features in the ultrafast transient absorption spectra of CdSe quantum dots

C. Zhang, T.N. Do, X. Ong, Y. Chan, H.-S. Tan

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

© 2016 Elsevier B.V.We describe a model to explain the features of the ultrafast transient absorption (TA) spectra of CdSe core type quantum dots (QDs). The measured TA spectrum consists of contributions by the ground state bleach (GSB), stimulated emission (SE) and excited state absorption (ESA) processes associated with the three lowest energy transition of the QDs. We model the shapes of the GSB, SE and ESA spectral components after fits to the linear absorption. The spectral positions of the ESA components take into account the biexcitonic binding energy. In order to obtain the correct weightage of the GSB, SE and ESA components to the TA spectrum, we enumerate the set of coherence transfer pathways associated with these processes. From our fits of the experimental TA spectra of 65 Å diameter QDs, biexcitonic binding energies for the three lowest energy transitions are obtained.
Original languageEnglish
Pages (from-to)157-164
JournalChemical Physics
Volume481
DOIs
Publication statusPublished - 20 Dec 2016
Externally publishedYes

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