Positron annihilation rates in many polyatomic molecular gases are anomalously high. Qualitatively, this can be explained by positron capture in vibrational Feshbach resonances, which can occur for molecules with positive positron a?nities [Gribakin, Phys. Rev. A 61 (2000) 022720]. To verify this idea quantitatively, we examine the densities of vibrational excitation spectra of alkanes. To understand the energy dependence of the annihilation rates for alkanes, we propose that positron capture is mediated by vibrational doorway states, in which positron binding is accompanied by the excitation of fundamentals.
|Number of pages||6|
|Journal||Nuclear Instruments & Methods in Physics Research - Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - Jul 2004|
ASJC Scopus subject areas
- Surfaces, Coatings and Films
- Surfaces and Interfaces