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Updated: Jun 6, 2026

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Biexcitonic fine structure of CdSe nanocrystals probed by polarization-dependent two-dimensional photon echo
Cathy Y Wong1, Gregory D Scholes
1Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6 Canada.
Abstract:
The spectroscopy of colloidal CdSe nanocrystals is investigated using two-dimensional photon echo (2DPE) spectroscopy with copolarized and cross-polarized pulse sequences. Clearly resolved excited state absorption features are observed to beat at the frequency of the longitudinal-optical phonon, and the phase of this beating is found to be polarization-dependent. A simulation is performed using the excitonic and biexcitionic fine structure states predicted by theory, and the polarization-dependent beating allows each feature to be assigned to a particular excited state absorption pathway. Owing to their circularly polarized selection rules, the polarization-dependent 2DPE technique provides valuable insights into the spectroscopy of quantum dots. In particular, transient absorption features observed in pump-probe studies of CdSe quantum dots can now be assigned to specific fine structure transitions to the ground state biexciton.
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