Positron Annihilation Spectroscopy of Polymers and Rubbers
Polymers and Rubbers
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Bartoš, J. 2006. Positron Annihilation Spectroscopy of Polymers and Rubbers. Encyclopedia of Analytical Chemistry.
- Published Online: 15 SEP 2006
Positron annihilation spectroscopy (PAS) is a common name for a set of techniques based on measurements and analysis of the annihilation characteristics of a positron e+ and its bound form with an electron e−, so-called positronium (e+e−) ≡ Ps. PAS includes three basic techniques:
Positron annihilation lifetime spectroscopy (PALS)
Angular correlation of annihilation radiation (ACAR)
Doppler broadening spectroscopy (DBS).
These techniques measure the time of emission, energies and momenta of positron–electron annihilation photons, respectively. PALS measures positron and positronium lifetimes and their relative intensities, giving information about the structural–physical properties of condensed materials such as metals, ceramics and polymers, while ACAR and DBS provide information about the electron momentum and energy distribution in a material. The first technique is the most developed and it serves to characterize the microstructural features of the disordered phase of condensed matter, such as defects or free-volume holes.