ABSTRACT
The collision of electrons with molecules as a fundamental process is dealt with in many areas of physics, astrophysics, chemistry, technology, and even biology. This book has its purpose in describing some recent advances in experimental and theoretical studies of the processes of electron-molecule scattering. The scattering processes have been studied for many years and important results have been obtained. For an excellent introduction to the physics of electron-molecule collisions, we refer the readers to the book by Shimamura and Takayanagi (1984). A comprehensive description of the theory of electron scattering with polyatomic molecules can be found in Gianturco and Jain (1986). The problem of low-energy electron scattering, to which the present book is devoted, is, however, much more complicated than that at intermediate-and high-energy regions (Khare 2002). At high energies, various approximations (e.g., Born or Glauber approximations) can be used with success. At low energy, however, demanding ab initio calculations must be performed. Even at the experimental side the low-energy scattering process encounters many problems. Among others, it is dif“cult to provide an electron beam with the energy
1.1 Physics of Low-Energy Electron-Molecule Collisions ....................................1 1.2 Organization of the Book .................................................................................5 Acknowledgment .......................................................................................................6 References ..................................................................................................................6
resolution of several meV stable down to the meV range, which is needed to study “ne resonance structures in the respective cross sections. On the theoretical side at low electron energies, processes like polarization of the target and electron correlation become essential and must be treated at an ab initio level. Most calculations on electron-molecule scattering have been performed with nuclear degrees of freedom frozen, the so-called “xed nuclei approximation. This approximation is the basic approximation in the electronic molecular structure theory. The nuclei are slow as compared to the swift motion of electrons and can, in “rst approximation, be treated as frozen. In any realistic scattering process, however, the nuclei move and the molecular degrees of freedom can be excited or the molecule can be disintegrated even at very low electron energies. It is obviously necessary to go beyond the “xednuclei approximation if we want to describe the processes in which the energy is transferred from light electrons to heavy nuclei. To describe processes of this type is one of the main purposes of this book.
