Effect of molecular constitution and conformation on positron binding and annihilation in alkanes

Abstract

The model-potential approach previously developed by the authors to study positron interactions with molecules is used to calculate the positron binding energy for $n$-alkanes (C${}_n$H${}_{2n+2}$) and the corresponding cycloalkanes (C${}_n$H${}_{2n}$). For $n$-alkanes, the dependence of the binding energy on the conformation of the molecule is investigated, with more compact structures showing greater binding energies. As a result, thermally averaged binding energies for larger alkanes ($n\gtrsim 9$) show a strong temperature dependence in the range of 100-600 K. This suggests that positron resonant annihilation can be used as a probe of rotational (trans-gauche) isomerization of $n$-alkanes. In particular, the presence of different conformers leads to shifts and broadening of vibrational Feshbach resonances in the annihilation rate, as observed with a trap-based low-energy positron beam.

arXiv comment17 pages, 13 figures

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Cited by in corpus (4)

• Effect of chlorination on positron binding to hydrocarbons: experiment and theory
• Many-Body Theory Calculations of Positron Scattering and Annihilation in H${}_2$, N${}_2$ and CH${}_4$
• Positron annihilation and binding in aromatic and other ring molecules
• Many-body theory predictions of positron binding energies in five-membered heterocycles involving N, O, S and NH substituents