Energy - resolved positron - molecule annihilation : Vibrational Feshbach resonances and bound states
نویسندگان
چکیده
OF THE DISSERTATION Energy-resolved positron-molecule annihilation: Vibrational Feshbach resonances and bound states
منابع مشابه
Enhancement of positron annihilation on molecules due to vibrational Feshbach resonances
The zero-range potential model is used to investigate positron collisions and annihilation with molecules. The Kr2 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 Kr2. (ii) A sequence of vibrationally excited states of the positron–molecule complex extends into the positron continuum, where it manifest...
متن کاملPositron-molecule interactions: Resonant attachment, annihilation, and bound states
This article presents an overview of current understanding of the interaction of low-energy positrons with molecules with emphasis on resonances, positron attachment, and annihilation. Measurements of annihilation rates resolved as a function of positron energy reveal the presence of vibrational Feshbach resonances VFRs for many polyatomic molecules. These resonances lead to strong enhancement ...
متن کاملRole of binding energy in Feshbach-resonant positron-molecule annihilation.
Measurements of positron-on-molecule annihilation have established that positrons bind to a variety of molecules via vibrational Feshbach resonances. Data for deeply bound states in benzene and 1-chlorohexane and for positronically excited (i.e., second) bound states in alkanes are used to establish the dependence of annihilation rates on the binding energy and incident positron energy. With th...
متن کاملDipole enhancement of positron binding to molecules.
Measurements of positron-molecule binding energies are made for molecules with large permanent dipole moments (>2.7 D), by studying vibrational-Feshbach-mediated annihilation resonances as a function of incident positron energy. The binding energies are relatively large (e.g., ≥90 meV) as compared to those for similar sized molecules studied previously and analogous weakly bound electron-mole...
متن کاملUbiquitous nature of multimode vibrational resonances in positron-molecule annihilation.
Positron annihilation on many molecules occurs via positron capture into vibrational Feshbach resonances, with annihilation rates often further enhanced by energy transfer to vibrational excitations weakly coupled to the positron continuum. Data presented here uncover another scenario in which the positron couples directly to a quasicontinuum of multimode vibrational states. A model that assume...
متن کامل