Threshold Energies for Single-Carbon Knockout from Polycyclic Aromatic Hydrocarbons
Number of Authors: 9
2015 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 6, no 22, 4504-4509 p.Article in journal (Refereed) Published
We have measured absolute cross sections for ultrafast (femtosecond) single-carbon knockout from polycyclic aromatic hydrocarbon (PAR) cations as functions of He-PAR center-of-mass collision energy in the 10-200 eV range. Classical molecular dynamics (MD) simulations cover this range and extend up to 105 eV. The shapes of the knockout cross sections are well-described by a simple analytical expression yielding experimental and MD threshold energies of E-th(Exp) = 32.5 +/- 0.4 eV and E-th(MD) = 41.0 +/- 0.3 eV, respectively. These are the first measurements of knockout threshold energies for molecules isolated in vacuo. We further deduce semiempirical (SE) and MD displacement energies, i.e., the energy transfers to the PAH molecules at the threshold energies for knockout, of T-disp(SE) = 23.3 +/- 0.3 eV and T-disp(MD) = 27.0 +/- 0.3 eV. The semiempirical results compare favorably with measured displacement energies for graphene (T-disp = 23.6 eV).
Place, publisher, year, edition, pages
2015. Vol. 6, no 22, 4504-4509 p.
Research subject Physics
IdentifiersURN: urn:nbn:se:su:diva-124747DOI: 10.1021/acs.jpclett.5b02080ISI: 000365460700010OAI: oai:DiVA.org:su-124747DiVA: diva2:893264