Loss of a C2H n fragment from pyrene and circumcoronene

  • Charles W. BauschlicherJr.Email author
  • Alessandra Ricca
Regular Article
Part of the following topical collections:
  1. Shavitt Memorial Festschrift Collection


Reactions at the edge of pyrene and circumcoronene are studied using the B3LYP approach in conjunction with the 4-31G and 6-31G** basis sets. The loss of a C2H n fragment from the edge of either molecule requires more than 7 eV, which is much larger than for the loss of an H atom. Some paths can be broken down into a series of less energetic steps, but this does not change the overall endothermicity of the process. The exception is a path where a hydrogen atom adds to pyrene or circumcoronene. The resulting molecule rearranges to have a \(\hbox {C}_2\hbox {H}_2\) side group, which is subsequently lost. This process has an overall endothermicity of only about 2.5 eV. This path is actually less endothermic than the loss of an H atom from the same species.


DFT Polycyclic aromatic hydrocarbon Loss of C2Hn 



AR thanks NASA’s Astrophysics Theory and Fundamental Physics (ATFP) (NNX09AD18G) program for its generous support of this work.


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Copyright information

© Springer-Verlag Berlin Heidelberg (outside the USA) 2014

Authors and Affiliations

  1. 1.Entry Systems and Technology DivisionNASA Ames Research CenterMoffett FieldUSA
  2. 2.Carl Sagan CenterSETI InstituteMountain ViewUSA

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