Picosecond dynamics of internal exciton transitions in CdSe nanorods

The picosecond dynamics of excitons in colloidal CdSe nanorods are directly measured via their 1sto 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 ons...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2013-12, Vol.88 (24), Article 241307
Main Authors: Cooke, D. G., Jepsen, P. Uhd, Lek, Jun Yan, Lam, Yeng Ming, Sy, F., Dignam, M. M.
Format: Article
Language:English
Subjects:
Cadmium selenides
Condensed matter
Dynamics
Excitation
Excitation spectra
Intermetallics
Nanorods
Phonons
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Summary:The picosecond dynamics of excitons in colloidal CdSe nanorods are directly measured via their 1sto 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.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.88.241307