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Title: Carbon nanorings with inserted acenes: Breaking symmetry in excited state dynamics

Abstract

Conjugated cycloparaphenylene rings have unique electronic properties being the smallest segments of carbon nanotubes. Their conjugated backbones support delocalized electronic excitations, which dynamics is strongly influenced by cyclic geometry. Here we present a comparative theoretical study of the electronic and vibrational energy relaxation and redistribution in photoexcited cycloparaphenylene carbon nanorings with inserted naphthalene, anthracene, and tetracene units using non-adiabatic excited-state molecular dynamics simulations. Calculated excited state structures reflect modifications of optical selection rules and appearance of low-energy electronic states localized on the acenes due to gradual departure from a perfect circular symmetry. After photoexcitation, an ultrafast electronic energy relaxation to the lowest excited state is observed on the time scale of hundreds of femtoseconds in all molecules studied. Concomitantly, the efficiency of the exciton trapping in the acene raises when moving from naphthalene to anthracene and to tetracene, being negligible in naphthalene, and ~60% and 70% in anthracene and tetracene within the first 500 fs after photoexcitation. Observed photoinduced dynamics is further analyzed in details using induced molecular distortions, delocatization properties of participating electronic states and non-adiabatic coupling strengths. Lastly, our results provide a number of insights into design of cyclic molecular systems for electronic and light-harvesting applications.

Authors:
 [1];  [1];  [2];  [1]
  1. Univ. Nacional de Quilmes/CONICET, Bernal (Argentina)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1321781
Report Number(s):
LA-UR-16-24517
Journal ID: ISSN 2045-2322
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Material Science

Citation Formats

Franklin-Mergarejo, R., Alvarez, D. Ondarse, Tretiak, S., and Fernandez-Alberti, S. Carbon nanorings with inserted acenes: Breaking symmetry in excited state dynamics. United States: N. p., 2016. Web. doi:10.1038/srep31253.
Franklin-Mergarejo, R., Alvarez, D. Ondarse, Tretiak, S., & Fernandez-Alberti, S. Carbon nanorings with inserted acenes: Breaking symmetry in excited state dynamics. United States. doi:10.1038/srep31253.
Franklin-Mergarejo, R., Alvarez, D. Ondarse, Tretiak, S., and Fernandez-Alberti, S. Wed . "Carbon nanorings with inserted acenes: Breaking symmetry in excited state dynamics". United States. doi:10.1038/srep31253. https://www.osti.gov/servlets/purl/1321781.
@article{osti_1321781,
title = {Carbon nanorings with inserted acenes: Breaking symmetry in excited state dynamics},
author = {Franklin-Mergarejo, R. and Alvarez, D. Ondarse and Tretiak, S. and Fernandez-Alberti, S.},
abstractNote = {Conjugated cycloparaphenylene rings have unique electronic properties being the smallest segments of carbon nanotubes. Their conjugated backbones support delocalized electronic excitations, which dynamics is strongly influenced by cyclic geometry. Here we present a comparative theoretical study of the electronic and vibrational energy relaxation and redistribution in photoexcited cycloparaphenylene carbon nanorings with inserted naphthalene, anthracene, and tetracene units using non-adiabatic excited-state molecular dynamics simulations. Calculated excited state structures reflect modifications of optical selection rules and appearance of low-energy electronic states localized on the acenes due to gradual departure from a perfect circular symmetry. After photoexcitation, an ultrafast electronic energy relaxation to the lowest excited state is observed on the time scale of hundreds of femtoseconds in all molecules studied. Concomitantly, the efficiency of the exciton trapping in the acene raises when moving from naphthalene to anthracene and to tetracene, being negligible in naphthalene, and ~60% and 70% in anthracene and tetracene within the first 500 fs after photoexcitation. Observed photoinduced dynamics is further analyzed in details using induced molecular distortions, delocatization properties of participating electronic states and non-adiabatic coupling strengths. Lastly, our results provide a number of insights into design of cyclic molecular systems for electronic and light-harvesting applications.},
doi = {10.1038/srep31253},
journal = {Scientific Reports},
number = ,
volume = 6,
place = {United States},
year = {Wed Aug 10 00:00:00 EDT 2016},
month = {Wed Aug 10 00:00:00 EDT 2016}
}

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