Vacancy migration and void formation in. gamma. -irradiated ice

Journal Article · Tue Jun 15 04:00:00 EDT 1976 · J. Chem. Phys.; (United States)

OSTI ID:7354654

Eldrup, M

Positron annihilation techniques (PAT) have been used to study the effects in ice of ..gamma.. irradiation at -196degreeC and of subsequent heating, both in poly- and monocrystalline samples. The main effects of irradiation are (1) the appearance in positron lifetime spectra of two long-lived components (1.2 and 2.3 nsec) ascribed to ortho-positronium (ortho-Ps) trapping in radiation created mono- and divacancies, (2) a strong decrease of the intensity of a short-lived component in the spectra, associated with para-Ps, and (3) an increase in the width of Doppler broadening spectra. The two latter effects are ascribed to Ps inhibition and conversion by radiation created OH radicals. Heating above -165degreeC makes both effects disappear in agreement with radiation chemistry results on OH. Heating also increases the longest lifetime up to 11 nsec at -130degreeC. This is explained as vacancy migration leading to void formation. A vacancy migration energy is obtained, E/subm/=0.34 +- 0.07 eV, around three times higher than the previously assumed value. The advantage in this kind of study of using PAT, which are specifically sensitive to vacancy type defects, is pointed out. (AIP)

• Research Organization: Chemistry Department, Research Establishment Riso, 4000 Roskilde, Denmark
• OSTI ID: 7354654
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 64:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600 -- Radiation Chemistry
640303* -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
74 ATOMIC AND MOLECULAR PHYSICS
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DECOMPOSITION
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
GAMMA RADIATION
ICE
INTERACTIONS
IONIZING RADIATIONS
LEPTONS
POINT DEFECTS
POSITRONIUM
POSITRONS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADIOLYSIS
VACANCIES