Аннотация:The present review deals with experimental and theoretical studies of ionization processes accompanying collisions between low-energy atomic particles (so-called chemoionization processes). Particular attention is given to new research trends in the physics of atomic collisions, in particular to studies of electron tear away processes, aimed at gaining insight into the dynamics, energetics, and the electron mechanism of the process, using particles with reliably identified states. A critical analysis is attempted of new results (and new methods) of experimental studies of charged particle production by collisions at energies below the characteristic ionization potentials. Some aspects of chemoionization with participation of electron-excited particles (Penning ionization) are discussed.