CHEMICAL-REACTIONS OF POSITRONIUM STUDIED BY AGE-MOMENTUM CORRELATION(AMOC) USING A RELATIVISTIC POSITRON BEAM

Correlated measurements of the individual positron lifetimes (so-calle d positron ages) and of the Doppler shift of the 2 gamma-annihilation photon energy (Age-Momentum Correlation, AMOC) allow the evolution of the positron states to be observed in the time domain. The AMOC techni que is thus especially useful when ''chemical'' reactions of positroni um induce transitions between positron states. The fun information con tained in the AMOC data may be extracted from the two-dimensional AMOC histogram, the so-called AMOC relief, by fitting a suitable two-dimen sional model function. In this way quantitative information on the spi n conversion of positronium by a paramagnetic radical in the systems H TEMPO/methanol and HTEMPO/benzene and on the formation of positron bou nd states in aqueous solutions of various sodium halides has been dedu ced.