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Investigating the Dynamics of 1D Excitons in Semiconductor Quantum Wires

Event Details

Event Dates: 

Friday, December 11, 2015 - 4:00pm

Seminar Location: 

  • JILA Auditorium

Speaker Name(s): 

Rich Loomis

Speaker Affiliation(s): 

Washington University in St. Louis
Seminar Type/Subject

Scientific Seminar Type: 

  • Phys Chem/Chem Phys Seminar

Event Details & Abstract: 

We are investigating the dynamics of charge carriers in one-dimensional (1D) semiconductor quantum wires (QWs), nanoparticles with small radii and lengths that span microns. While the nature of electron-hole pairs photogenerated within semiconductor QWs should resemble quantum mechanical particles in a cylinder, the basics of these systems are not fully understood. We are using a number of cw and time-resolved microscopy techniques to characterize the energetics and dynamics of electron-hole pairs in CdSe and CdTe/CdS QWs. Specifically, we are investigating: a) the energetics of the electrons and holes that are perturbed by the small radial dimensions of the QWs; b) the electron-hole interactions that result from Coulombic forces and self-imaging effects; and c) the free-wave nature of bound electron-hole pairs, or 1D excitons, along the lengths of the QWs. Interestingly, as 1D excitons diffuse along a QW the electron-hole pairs cannot recombine radiatively due to conservation of momentum constraints. As a result, we observe the delocalization of 1D excitons along the entire lengths of CdSe QWs, longer than 10 µm. In addition, the photoluminescen​ce lifetimes are observed to be