טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentGordon Eli
SubjectCollisions of Fullerenes with Bare and Overlayer Covered
Surfaces
DepartmentDepartment of Chemistry
Supervisor Professor Eliezer Kolodney


Abstract

    We have studied collisional processes of low energy (100-2000 eV) C60 projectiles with clean surfaces and amino acid overlayer covered surfaces. Our experiments were conducted under UHV (Ultra High Vacuum) conditions. For production of the primary projectiles beam we used home made /Cs+ ion source. For the purpose of on-line coating of the surfaces with amino acids overlayers we have constructed an evaporation source that produces a directed thermal beam, thus enabling continuous growth leading to steady state (growth / etching) conditions.

    Two different types of collisional processes were explored: I) Surface induced disintegration (multi-fragmentation) of the C60 molecule. Surface Induced Dissociation (SID) of C60 projectiles with 300-1000 eV kinetic energies was observed at near-grazing and near-normal scattering conditions. The surface in these experiments was an atomically clean polycrystalline gold surface. In order to deduce the fragmentation mechanisms of the C60 collider we have recorded energy distributions and angular dependencies for as many  fragments as possible. II) Secondary Ion Mass Spectrometry (SIMS) of overlayer molecules induced by C60 collisions. We have measured the secondary ion emission from amino acid covered (glycine and leucine) metallic surfaces induced by 100-2000 eV impacts of  projectiles. The secondary ion emission induced by the C60 molecular projectile was compared to the emission induced by an atomic Cs+ projectile. Growth kinetic experiments of the amino acid overlayer and kinetic energy distributions of emitted secondary ions are reported as well. We have found a mechanistic correlation between the fragmentation of the C60 cluster on the surface to the fragmentation and sputtering yield of the amino acid overlayer induced by its impact.