Cooke, D. G.7; Jepsen, Peter Uhd4; Lek, Jun Yan5; Lam, Yeng Ming5; Sy, F.6; Dignam, M. M.6
1 Department of Photonics Engineering, Technical University of Denmark2 Teraherts Technologies and Biophotonics, Department of Photonics Engineering, Technical University of Denmark3 McGill University4 Center for Nanostructured Graphene, Center, Technical University of Denmark5 Nanyang Technological University6 Queen's University7 McGill University
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.
Physical Review B (condensed Matter and Materials Physics), 2013, Vol 88, Issue 24