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Femtosecond Electronic Spectroscopy of Nanostructures 

The objective of this program is to learn ultrafast dynamics of excitons and charge carriers in fundamentally important and technologically relevant semiconducting nano-scale systems. We are seeking quantitative information about the characteristic timescales of exciton relaxation and migration, charge separation, transfer and recombination, as well as their potential correlation to material properties and spatial confinement. Our spectroscopic techniques include femtosecond two-pulse photon echo, frequency-resolved transient absorption and time-resolved fluorescence.

Project Results
Experimental setup
bullettIntensity dependence of exciton relaxation in CuPc nanowires

Experimental Setup for Transient Absorption Measurements


Intensity Dependence of Exciton Relaxation in CuPc Nanowiresnanowire graphic


Representative data collected at 594 nm for α-phase copperphthalocyanine single-crystal nanowires (provided by Dr. Kai Xiao, CNMS). The observed dependence of transient absorption kinetics on excitation intensity is evident of occurrence of an exciton-exciton annihilation process.




bullettUltrafast Optical Spectroscopy


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Provided by Oak Ridge National Laboratory's Chemical Sciences Division
Rev:  February 2013