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Title: Influence of Exciton Dimensionality on Spectral Diffusion of Carbon Nanotubes.


Abstract not provided.

Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the MRS Spring 2015 held April 6-10, 2015 in San Francisco, CA.
Country of Publication:
United States

Citation Formats

Ma, Xuedan. Influence of Exciton Dimensionality on Spectral Diffusion of Carbon Nanotubes.. United States: N. p., 2015. Web.
Ma, Xuedan. Influence of Exciton Dimensionality on Spectral Diffusion of Carbon Nanotubes.. United States.
Ma, Xuedan. 2015. "Influence of Exciton Dimensionality on Spectral Diffusion of Carbon Nanotubes.". United States. doi:.
title = {Influence of Exciton Dimensionality on Spectral Diffusion of Carbon Nanotubes.},
author = {Ma, Xuedan},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 4

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  • Semiconducting single-walled carbon nanotubes (SWNTs) are one of the most intriguing nanomaterials due to their large aspect ratios, size tunable properties, and dominant many body interactions. While the dynamics of exciton population relaxation have been well characterized, optical dephasing processes have only been exam- ined indirectly through steady-state measurements such as single-molecule spectroscopy that can yield highly variable estimates of the homogeneous linewidth. To bring clarity to these conflicting estimates, a time-domain measurement of exciton dephasing at an ensemble level is necessary. Using two-pulse photon echo (2PE) spec- troscopy, comparatively long dephasing times approaching 200 fs are extracted for themore » (6,5) tube species at room temperature. In this contribution, we extend our previous study of 2PE and pump-probe spectroscopy to low temperatures to investigate inelastic exciton-exciton scattering. In contrast to the population kinetics observed upon excitation of the second transition-allowed excitonic state (E22 ), our one-color pump-probe data instead shows faster relaxation upon cooling to 60 K when the lowest transition-allowed state (E11 ) is directly excited for the (6,5) tube species. Analysis of the kinetics obtained suggests that the observed acceleration of kinetic decay at low temperature originates from an increasing rate of exciton-exciton annihilation. In order to directly probe exciton-exciton scattering processes, femtosecond 2PE signal is measured as a function of excitation fluence and temperature. Consistent with the observed enhancement of exciton-exciton scattering and annihilation at low temperatures, the dephasing rates show a correlated trend with the temperature dependence of the population lifetimes extracted from one-color pump-probe measurements.« less
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  • Recent experimental work has shown that membranes containing aligned carbon nanotubes exhibit transport rates for gases and liquids that are orders of magnitude larger than rates predicted from Knudsen or hydrodynamic no-slip flow. We present atomically detailed simulations of diffusion of water and alkanes through single-walled carbon nanotubes. The self, corrected, and transported diffusivities are calculated for liquid-like densities of water and alkanes in nanotubes using equilibrium molecular dynamics, with thermodynamic correction factors computed from Monte Carlo adsorption isotherm calculations. We also present the zero-coverage diffusivities for these fluids. We discuss the results in comparison with bulk fluid self-diffusivities andmore » experimental data for flow through nanotubes membranes.« less
  • The rate of decay of triplet excitons following a photoexcitation pulse has been determined for poly(2-vinylnaphthalene) in a variety of solvents at ambient temperature and at 77 K. A three dimensional model for exciton diffusion fits the data at ambient temperature but at 77 K the data are not well represented by a single integral dimensionality. 7 refs., 1 tab.