31 research outputs found
Excited State Dynamics of Individual Single-Walled Carbon Nanotubes
In this work we tried to shed light on issue by excited state dynamics in carbon nanotubes by combining the photoluminescence (PL) spectroscopy with the time-resolved PL studies from single carbon nanotubes at room temperature
Coherent Control of Light Scattering from Nanostructured Materials by Second-Harmonic Generation
We introduce an active, all-optical method for controlling the intensity and directionality of light scattering from single nanostructures. The method is based on the coherent interplay between linear light scattering and second-harmonic generation. The intensity and directionality of scattered light can be controlled by the phase delay and the relative angle between excitation beams. We discuss the principle of this coherent control technique and perform numerical model calculations
Defect Induced Photoluminescence from Dark Excitonic States in Individual Single-Walled Carbon Nanotubes
We show that new low-energy photoluminescence (PL) bands can be created in
semiconducting single-walled carbon nanotubes by intense pulsed excitation. The
new bands are attributed to PL from different nominally dark excitons that are
"brightened" due to defect-induced mixing of states with different parity
and/or spin. Time-resolved PL studies on single nanotubes reveal a significant
reduction of the bright exciton lifetime upon brightening of the dark excitons.
The lowest energy dark state has longer lifetimes and is not in thermal
equilibrium with the bright state.Comment: 4 pages, 3 figure
Metal-Enhanced Fluorescence of Chlorophylls in Single Light-Harvesting Complexes
Ensemble and single-molecule spectroscopy demonstrates that both emission and absorption of peridinin−chlorophyll−protein photosynthetic antennae can be largely enhanced through plasmonic interactions. We find up to 18-fold increase of the chlorophyll fluorescence for complexes placed near a silver metal layer. This enhancement, which leaves no measurable effects on the protein structure, is observed when exciting either chlorophyll or carotenoid and is attributed predominantly to an increase of the excitation rate in the antenna. The enhancement mechanism comes from plasmon-induced amplification of electromagnetic fields inside the complex. This result is an important step toward applying plasmonic nanostructures for controlling the optical response of complex biomolecules and improving the design and functioning of artificial light-harvesting systems
Exciton decay dynamics in individual carbon nanotubes at room temperature
We studied the exciton decay dynamics of individual semiconducting single-walled carbon nanotubes at room temperature using time-resolved photoluminescence spectroscopy. The photoluminescence decay from nanotubes of the same (n,m) type follows a single exponential decay function, however, with lifetimes varying between about 1 and 40 ps from nanotube to nanotube. A correlation between broad photoluminescence spectra and short lifetimes was found and explained by defects promoting both nonradiative decay and vibronic dephasing