منابع مشابه
Feshbach-resonance-mediated positron annihilation in small molecules
Large positron annihilation cross sections have been observed for a variety of molecules at various energies below the threshold for positronium formation. These large values are due to vibrational Feshbach resonances VFRs , in which the positron attaches to the molecule while exciting a vibration. This leads to rates of annihilation far greater than those expected for a simple collision. The d...
متن کاملMechanisms of positron annihilation on molecules
The aim of this work is to identify the mechanisms responsible for very large rates and other peculiarities observed in low-energy positron annihilation on molecules. The two mechanisms considered are: (i) Direct annihilation of the incoming positron with one of the molecular electrons. This mechanism dominates for atoms and small molecules. I show that its contribution to the annihilation rate...
متن کاملPositron Annihilation on Atoms and Molecules
OF THE DISSERTATION Positron Annihilation on Atoms and Molecules
متن کاملVibrational-resonance enhancement of positron annihilation in molecules.
The rate of annihilation of low-energy positrons in many molecular gases is orders of magnitude larger than can be explained on the basis of simple collisions. Developments in positron beam technology have enabled the first energy-resolved measurements of this annihilation process. The results of these experiments provide direct evidence that the large observed values of annihilation rate are d...
متن کاملRole of vibrational dynamics in resonant positron annihilation on molecules.
Vibrational Feshbach resonances are dominant features of positron annihilation for incident positron energies in the range of the molecular vibrations. Studies in relatively small molecules are described that elucidate the role of intramolecular vibrational energy redistribution into near-resonant multimode states, and the subsequent coupling of these modes to the positron continuum, in suppres...
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ژورنال
عنوان ژورنال: Journal of Physics B: Atomic, Molecular and Optical Physics
سال: 2013
ISSN: 0953-4075,1361-6455
DOI: 10.1088/0953-4075/46/19/195001