Picosecond dynamics of internal exciton transitions in CdSe nanorods

D. G. Cooke, Peter Uhd Jepsen, Jun Yan Lek, Yeng Ming Lam, F. Sy, M. M. Dignam

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Abstract

The picosecond dynamics of excitons in colloidal CdSe nanorods are directly measured via their 1s to 2p-like internal transitions by ultrabroadband terahertz spectroscopy. Broadened absorption peaks from both the longitudinal and transverse states are observed at 8.5 and 11 THz, respectively. The onset of exciton-LO phonon coupling appears as a bleach in the optical conductivity spectra at the LO phonon energy for times > 1 ps after excitation. Simulations show a suppressed exciton temperature due to thermally excited hole states being rapidly captured onto ligands or unpassivated surface states. The relaxation kinetics are manipulated and the longitudinal transition is quenched by surface ligand exchange with hole capturing pyridine.
Original languageEnglish
Article number241307
JournalPhysical Review B Condensed Matter
Volume88
Issue number24
Number of pages5
ISSN0163-1829
DOIs
Publication statusPublished - 2013

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Copyright 2013 American Physical Society.

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