TABLE OF CONTENTS K.S vegh 1 , T.Marek 2
1 Department of Nuclear Chemistry, E tv s Lor nd University, Budapest, Hungary
2 Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences at E tv s Lor nd University, Budapest, Hungary
This chapter demonstrates the applicability of positrons in nuclear chemistry and material sciences. From the very basics to highly developed spectroscopic methods we give a brief outline of positron annihilation spectroscopies. The possibilities of these methods are emphasized and characteristic applications are outlined for every one of them.
As positron annihilation spectroscopies are not conventional methods in studying materials, this chapter might need a more basic introduction than others. Consequently, below we briefly explain the very basics of positron annihilation spectroscopies. Additionally, we describe most variations of spectroscopies applying positrons as probes for material properties.
The positron is the antiparticle of the electron. It was theoretically deduced by Dirac (1930) and later observed by Anderson (1932) in cosmic rays. As any other antiparticle, the positron reflects its particle counterpart in every respect, their physical properties are equivalent. The masses of the two particles are identical and so are the absolute values of electric charges, spins and magnetic moments. However, the electric charge of the positron is positive causing its magnetic moment to point in the direction of its spin.
In a vacuum the positron is a stable particle but, in materials, annihilates with an electron rapidly. The particle/antiparticle pair disappears in the annihilation process producing gamma photons.
