pet (positron emission tomography) is a powerful imaging technique that can provide quantitative information on the distribution of positron emitter labeled radiopharmaceuticals (pet radiopharmaceuticals) in the body. positrons (ß+) are positively charged beta particles. they are emitted when the atom is proton rich. a positron has only a transient existence. after losing all of its kinetic ene...

We discuss the theory of electron-molecule excitation processes of importance in fusion plasmas. We consider elastic scattering, rotational, vibrational, and electronic excitation in turn and also dissociative attachment and impact dissociation.