Accession Number:

ADA276542

Title:

Positron-Molecule Interactions

Descriptive Note:

Final technical rept. 1 Oct 1989-31 Dec 1993

Corporate Author:

CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF PHYSICS

Personal Author(s):

Report Date:

1994-02-14

Pagination or Media Count:

9.0

Abstract:

The objective of this research was to study the interaction of positrons with molecules at energies below the threshold for positronium atom formation. While there is evidence that positrons bind, or form long-lived resonances with large atoms and molecules, this phenomenon is not understood. This phenomenon has a number of potentially important scientific and technological applications, including aspects of atomic and molecular physics, the formation of positive ions for mass spectrometry, and gamma ray astronomy. Many facets of the interaction of low-energy positrons with molecules were illuminated, including the scaling of positron annihilation rate with molecular ionization potential the identification of other trends as a function of chemical structure. Spectra of the gamma ray radiation resulting when a positron annihilates on a molecule were also measured. The measurements indicate that the site of positron binding is on the C-H bond in hydrocarbon molecules and on the fluorine atoms in fluorine compounds. The measured annihilation rates on large aromatics indicate that these molecules are likely to be an important source of the annihilation radiation observed from the interstellar medium. Positrons, Atomic and molecular physics, Annihilation radiation.

Subject Categories:

  • Inorganic Chemistry
  • Organic Chemistry
  • Atomic and Molecular Physics and Spectroscopy
  • Nuclear Physics and Elementary Particle Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE