Application of positron annihilation to the characterization of zeolites

Journal Article · Thu Oct 28 04:00:00 EDT 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100219a035· OSTI ID:6463281

Nakanishi, H; Ujihira, Y

Positron annihilation lifetime and Doppler-broadening measurements were carried out for synthetic zeolite 13X, SK-40, NH/sub 4/-X, and NH/sub 4/-Y by varying the evacuation temperature in order to study the character of the zeolite cages. Four components of the positron annihilation, derived from the lifetime spectra, were interpreted from the results of the authors' measurements and other studies on zeolites. The o-Ps lifetimes in the cages became longer as the desorption of water molecules proceeded. It was found that some active groups in zeolites interacted with o-Ps and reduced the o-Ps lifetime after all the water molecules had detected. Bronsted acid in the zeolite acted not only as an oxidizer but also as an inhibitor of Ps formation. An attempt was made to estimate the amount of Bronsted acids by the positron lifetime technique. The longest lifetime of 50 ns indicates o-Ps annihilation in a pore with 60 A free diameter, which seems to exist irregularly in the faujasite zeolites. It was found that o-Ps was oxidized in this large cavity.

• Research Organization: Univ. of Tokyo, Japan
• OSTI ID: 6463281
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:22; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
640303 -- Atomic
Molecular & Chemical Physics-- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules
74 ATOMIC AND MOLECULAR PHYSICS
ANNIHILATION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DOPPLER BROADENING
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
GAMMA RADIATION
INFORMATION
INORGANIC ION EXCHANGERS
INTERACTIONS
ION EXCHANGE MATERIALS
IONIZING RADIATIONS
LEPTONS
LIFETIME
LINE BROADENING
MATERIALS
MICROSTRUCTURE
MINERALS
NUMERICAL DATA
POROSITY
POSITRONS
RADIATIONS
TEMPERATURE EFFECTS
ZEOLITES