Experimental support for physisorbed positronium at the surface of quartz

Journal Article · Fri Nov 01 00:00:00 EST 1985 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.32.6067· OSTI ID:6448375

Sferlazzo, P; Berko, S; Canter, K F

We report temperature-dependent positronium (Ps) emission from a single crystal of SiO/sub 2/ using a monoenergetic positron beam. Slow positrons (e/sup +/) from an electrostatic beam system were injected with variable energy (0--1600 eV) into the SiO/sub 2/ target and Ps emission from the target surface was studied as a function of incident e/sup +/ energy (E) as well as target temperature (T). Our data suggest a physisorbed Ps surface state which is temperature activated into a ''slow'' Ps emission with an activation energy of approx.0.15 eV. In addition, a large Ps yield (40% of the incident positrons are emitted as Ps at 400 eV) is observed even for T..-->..0, attributed to ''fast'' Ps produced by the bulk Ps formed within the SiO/sub 2/ target and diffusing to the surface. From the Ps yield vs E we find a bulk Ps diffusion constant of 0.047 +- 0.013 cm/sup 2//sec. We also observe a slow e/sup +/ reemission yield of (15 +- 2)% at 400-eV incident e/sup +/ energy.

• Research Organization: Department of Physics, Brandeis University, Waltham, Massachusetts 02254
• OSTI ID: 6448375
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 32:9
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
POSITRONIUM
ABSORPTION
EMISSION
SILICON OXIDES
POSITRON COLLISIONS
DIFFUSION
EV RANGE
KEV RANGE
MONOCRYSTALS
POSITRON BEAMS
TEMPERATURE DEPENDENCE
ULTRAHIGH VACUUM
BEAMS
CHALCOGENIDES
COLLISIONS
CRYSTALS
ENERGY RANGE
LEPTON BEAMS
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
SILICON COMPOUNDS
640303* - Atomic
Molecular & Chemical Physics- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules