Dynamics of surface melting: Progress report, September 1, 1988--December 31, 1989

Technical Report · Sat Jul 01 04:00:00 EDT 1989

DOI:https://doi.org/10.2172/5703345· OSTI ID:5703345

Elsayed-Ali, H. E.

The objectives of this program is to study the phenomena of surface melting of single crystals of metals, to test for its existence, and to investigate its dynamics using picosecond reflection high-energy electron diffraction (RHEED). In this year, the UHV facility containing picosecond RHEED has become fully operational with a dedicated laser system and image acquisition capabilities. Details of this facility are described. This system was utilized to study surface heating and cooling of a PB(110) crystal subjected to picosecond laser irradiation. Diffraction pattern sensitivity to temperature is due to the surface Debye-Waller factor which results in a reduced number of elastically scattered electrons with lattice heating. Development of a picosecond time-resolved surface temperature probe is a key step to study the dynamics of surface melting that was well demonstrated in our present work. A heat diffusion model of surface heating and cooling has also been constructed. Results on static RHEED experiments on surface melting of Pb(110) crystal are presented. The existence of a surface melting (disordering) transformation at temperatures at least 50/degree/K below the bulk melting point was observed in our experiments. Quantitative RHEED study of this phenomena are in progress.

• Research Organization: Rochester Univ., NY (USA). Lab. for Laser Energetics
• DOE Contract Number: FG02-88ER45376
• OSTI ID: 5703345
• Report Number(s): DOE/ER/45376-1; ON: DE89016337
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
656002* -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COHERENT SCATTERING
CRYSTALS
DIFFRACTION
DOCUMENT TYPES
ELECTROMAGNETIC RADIATION
ELECTRON DIFFRACTION
ELEMENTS
LASER RADIATION
LEAD
MELTING
METALS
PHASE TRANSFORMATIONS
PROGRESS REPORT
RADIATIONS
SCATTERING
SURFACE PROPERTIES