Electron-Atom Collisions

Abstract

This book is a comprehensive introduction to electron-atom collisions, covering both theory and experiment. The interaction of electrons with atoms is the field that most deeply probes both the structure and reaction dynamics of a many-body system. The book begins with a short account of experimental techniques of cross-section measurement. It then introduces the essential quantum mechanics background needed. The following chapters cover one-electron problems (from the classic particle in a box to a relativistic electron in a central potential), the theory of atomic bound states, formal scattering theory, calculation of scattering amplitudes, spin-independent and spin-dependent scattering observables, ionisation and electron momentum spectroscopy. The connections between experimental and theoretical developments are emphasised throughout.

Superelastic Electron Scattering within a Magnetic Angle Changer: Determination of the Angular Momentum Transferred during Electron Excitation over All Scattering Angles

“…The detailed study of electron collision processes has a long history in the field of experimental atomic and molecular physics, with excitation [1] and ionization [2] of the target continuing to provide stringent tests of the most sophisticated theories. These comparisons are most exact when the momenta and character of the incident and scattered particles are determined in coincidence, since the differential cross section can then be ascertained.…”

Invited Article: An improved double-toroidal spectrometer for gas phase (e,2e) studies

“…This additional information would be required to directly relate the measured count rates to the triple-differential cross section. 1 However, the spectrometer can determine the relative variations of d 5 / d⍀ 1 d⍀ 2 dE 2 as a function of the emission angles 1 and 2 and energies E 1 and E 2 , over the analyzer acceptance ranges ⌬ 1 , ⌬ 2 , ⌬E 1 , and ⌬E 2 , if variations in detection efficiency with the angular and energy variables are taken into account. This is achieved in the following manner.…”

“…To obtain the most detailed information on this reaction, kinematically complete experiments must be performed in which the momenta of at least two of the three charged particles in the final state ͑compris-ing an ion and two electrons͒ are determined in a coincidence experiment. 1,2 The momentum of the third particle then follows from the law of momentum conservation. For the present spectrometer design, it is the momenta of the two final-state electrons which are determined in a so-called ͑e ,2e͒ experiment.…”

Super-elastic scattering from calcium over the complete angular range using a magnetic angle changing device

“…The study of electron collisions has a long history in atomic and molecular physics, with excitation 1 and ionization 2 of the target providing stringent tests of theory. These comparisons are most exact when particles from the collision are measured in coincidence, since the full differential cross section can then be determined.…”

“…In this method (figure 1), the atom is initially excited from the ground state using laser radiation of well defined polarization directed orthogonal to the scattering plane (1). The incident electrons are directed as shown (2), while the electron detector is positioned where the source would be located in a coincidence study. The detector then measures super-elastically scattered electrons that have the same energy as incident electrons in a coincidence experiment (3).…”