Jennifer Herdman - Computational and experimental evidence for polynuclear aromatic hydrocarbon aggregation in flames

Document created by Jennifer Herdman on Aug 22, 2014
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  Publication Details (including relevant citation   information):

  Citation: In Combustion Generated Fine   Carbonaceous Particles; Bockhorn, H., D'Anna, A., Sarofim, A. F.,   Wang, H., Eds.; Karlsruher Institute for Technology: Karlsruhe,   Germany, 2009, p 259-276.

  First Author: J. Houston Miller

  Institution: Department of Chemistry, The George   Washington University, Washington, District of Columbia 20052


  In the combustion of fossil or bio-derived fuels under rich   conditions, some fraction of the fuel carbon is converted into   fine particulate carbon. This carbonization process usually leads   to soot, a form of amorphous carbon characterized by small   primary particles aggregated into fractal structures. It is our   hypothesis that the most critical step in soot inception is the   transition from 2-dimensional to 3-dimensional structures and   that, for soot formation, this transition is the agglomeration of   polynuclear aromatic hydrocarbons of modest molecular size. In   the current paper, a review of available literature on   experimental observation of PAH in flames as well as   computational work that assesses the role of PAH condensation in   soot inception is presented. Results of recent atom-pair   calculations of intermolecular interactions of ****-molecular and   hetero-molecular clusters for many peri-condensed PAH spanning   monomer masses ranging from 78-1830 Da are presented. Binding   energies of ****-molecular dimers rise rapidly with molecular   size and asymptotically approach the experimentally established   exfoliation energy for graphite of 5.0 ± 0.5 kJ   (mol)-1(carbon atom)-1. Binding energies of   hetero-molecular dimers correlate well with the reduced mass of   the pair. From calculations of ****-molecular stacks, binding   energies were observed to increase with each added molecule and   rise asymptotically, approaching a limit which scales linearly   with monomer molecular mass.

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