This volume is concerned with the study of electron-molecule interactions
which are of particular importance in gas and plasma processing. When an
electron is scattered by a molecule it feels a nonspherical, multicentered
potential so that the scattering process is not simple. Quite frequently a
resonance occurs in the course of scattering that is due to the complex shape
of the molecular potential. Rotational and vibrational degrees of freedom
give rise to a large number of channels to be taken into account. Furthermore,
the nuclear motion can induce molecular dissociation. Particularly in
the case of polyatomic molecules the dissociation process results in a large
number of different fragments. These can be positively or negatively charged,
as well as neutral. It is sometimes difficult even to identify all of the fragment
species. In addition to the multiple channels of the collision process thus
indicated, the existence of an enormous number of different molecular
species in nature leads to a wide spectrum of collision phenomena. These
issues are actively discussed at the International Conference on the Physics
of Electronic and Atomic Collisions (ICPEAC) and its satellite meeting on
electron-molecule collisions every other year.