No abstract available

[en] The various factors which limit the attainable energy resolution in low energy electron-atom scattering experiments are discussed, and examples of recent high resolution studies are described

No abstract available

[en] A brief review is given of the apparent exchanges of energy that can occur sometimes between the outgoing particles in electron--atom impact experiments, when these final particles consist of two electrons receding from a positive ion, and when the incident electron energy is near the energy of an autoionizing state of the target atom. These energy exchanges manifest themselves as changes in the energies of electrons ejected from autoionizing states of atoms excited by near-threshold electron impact, displacements of the thresholds for exciting autoionizing states, and structure in the cross sections for exciting Rydberg states of neutral atoms by electron impact at incident energies in the vicinity of autoionizing states. The experimental evidence for these processes is reviewed and qualitative explanations are given. Evidence for analogous effects in other scattering and absorption processes is also discussed

[en] Published in summary form only, 19 refs

[en] The final-state Coulomb interaction between three or more outgoing charged particles from a reaction can cause exchanges of energy and angular momentum between them. Such exchanges may be present for example when the reaction products consist of two electrons receding from a positive ion. The experimental evidence for the existence of such effects in threshold ionization and threshold autoionization are reviewed, and their possible theoretical descriptions are discussed

[en] This review deals with three recent developments in the field of inner shell excitation of atoms and molecules by electron impact with high energy resolution, namely: (1) the observation of high resolution energy loss spectra for inner shell excited states, (2) the observation of inner shell excited resonances, and (3) the measurement and interpretation of effects caused by post-collision interactions following the decay of inner shell excited states. The inner shell states considered are those in the subshell immediately below the valence subshell, or in the next lower lying subshell or full shell

[en] The field of the direct measurement of atomic and molecular lifetimes has been characterized in the past few years by the development of several new and powerful techniques and by an improving ability to control and limit the measurement inaccuracies of older techniques. The establishment of a wide range of accurate values for atomic and molecular lifetimes is now possible. This review deals with the measurement of lifetimes of atoms and molecules in the gas phase, in the range 10^-10 to 10^-5s, and concentrates on the more accurate and promising techniques, which are grouped together according to whether their most prominent feature is the means of excitation or the interference between excited levels or the coincidence detection of two decay events. Possible sources of systematic error are discussed at length and the theoretical background appropriate to the measurements is given when necessary. The techniques and their areas of applicability are compared and the likely future development of them is discussed. (author)

[en] Many different types and geometries of electrostatic lenses have been used in the past to control beams of electrons or ions, but it is only in recent years that accurate information has been available on the focal properties and aberration coefficients of electrostatic lenses, enabling detailed design studies of lens systems to be undertaken. This review will deal firstly with the computational techniques, including the charge density technique, for evaluating lens properties. These lens properties are of several different types (such as focal lengths, mid-focal lengths and aberration coefficients), and are usually functions of several different parameters (for example, voltage ratios), and for the purpose of designing lens systems it is convenient for this information to be parametrised in the form of numerical approximations. The achievement of this will be discussed and examples will be given. In choosing the best lens and operating conditions for a given problem and set of restrictions it is usually possible to define a dimensionless figure of merit, and then to choose the lens by finding which one has the best value of this figure of merit. Examples of such figures of merit will be given, with illustrations of their use. Special classes of lenses, such as zoom lenses, will also be discussed. (author)

[en] This chapter presents early inner-shell excitation studies and high-resolution studies. A comparison of the photoabsorption and electron energy-loss techniques for making spectroscopic measurements in atoms and molecules is presented. Experimental details are given for the electron energy-loss technique. High-resolution studies of both atoms and molecules are examined