The zero-range potential model is used to investigate positron collisions and annihilation with molecules. The Kr dimer is considered as an example. It is shown that (i) although positrons do not bind to individual Kr atoms, they do form bound states with Kr. (ii) A sequence of vibrationally excited states of the positron-molecule complex extends into the positron continuum, where it manifests as vibrational Feshbach resonances. (iii) These resonances give a very large contribution to the positron annihilation rate. Even after averaging over the thermal positron energy distribution, the contribution of the lowest Feshbach resonance exceeds that of the non-resonant background by an order of magnitude.
|Number of pages||14|
|Journal||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - 01 May 2002|
ASJC Scopus subject areas
- Surfaces, Coatings and Films
- Surfaces and Interfaces