Abstract
The zero-range potential model is used to investigate positron collisions and annihilation with molecules. The Kr 2 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 2. (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.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
