منابع مشابه
Nuclear-Charge Screening in Positronium Formation from Helium Atoms
An analytical treatment of the electron screening effect within an active-electron model is given for positronium formation from helium atoms. A first-order distorted wave approximation with correct boundary conditions is applied to evaluate the transition amplitude. In the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sect...
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The three positron based chemical entities, analogous to hydrogen atom, hydrogen molecule and hydride, are drawing increasing attention in the literature. While a lot is known about the binding energies, not much is known about the radii of the atoms and ions and bond lengths and structures of these exotic entities. This article brings for the first time exact values of these structural propert...
متن کاملOptical spectroscopy of molecular positronium.
We report optical spectroscopic measurements of molecular positronium (Ps(2)), performed via a previously unobserved L=1 excited state. Ps(2) molecules created in a porous silica film, and also in vacuum from an Al(111) crystal, were resonantly excited and then photoionized by pulsed lasers, providing conclusive evidence for the production of this molecular matter-antimatter system and its exci...
متن کاملIonization and positronium formation in noble gases
Absolute measurements are presented for the positron-impact cross sections for direct ionization and positronium formation of noble gas atoms in the range of energies from threshold to 90 eV. The experiment uses a cold, trap-based positron beam and the technique of studying positron scattering in a strong magnetic field. The current data show generally good, quantitative agreement with previous...
متن کاملPositronium Formation in Solid Long-Chain Alkanes
This paper represents a fragment of systematic studies on positron annihilation in solid saturated hydrocarbons (alkanes, paraffins) from C17H36 to C30H62. The Tao–Eldrup model and its extensions allow to identify the places in the crystalline structure where positronium is trapped, and estimate respective trap sizes. In the rigid phase I positronium locates mainly in two-dimensional empty spac...
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ژورنال
عنوان ژورنال: Journal of Physics: Conference Series
سال: 2013
ISSN: 1742-6596
DOI: 10.1088/1742-6596/443/1/012001