NCAT PHYSICS COLLOQUIUM SIRIES
2007/2008
Contact: Dr. Abebe Kebede
336-285 2113 or email abkebede@gmail.com






  Dr.Petros Thomas







PetrosThonas (PhD)

University of Virgina
Deparment of Physics
E-mail :  petros.thomas@gmail.com
Web: Website

October 13, 2008
Marteenal Hall Room 310  Monday 4:00 PM
Title: Probing Surface Phenmenon Using Optical Techinques


Abstract

Optical techniques have proven to be very useful to characterize various surface phenomenon in situ; such as, sub-monolayer and monolayer adsorption, multilayer and thin film growth, desorption, diffusion, orientation of molecules on surfaces, and displacement transitions (displacement of a pre-adsorbed species by another adsorbate). Optical techniques are mostly non intrusive which makes them ideal for a wide range of pressure. In this talk, first I will demonstrate the use of an oblique incidence reflectivity difference technique for adsorption, growth, and desorption studies of Xe and H on metal surfaces in a relatively lower pressure range (maximum dosing pressure of 1 × 10-6 Torr). I will also discuss the use of a linear optical diffraction technique to probe diffusion of adsorbates on metal surfaces. Then I will talk about a recent study of binary mixtures of simple molecules on a graphite surface at a relatively higher pressure range (dosing pressure from a few millitorr up to a few torr) using ellipsometry and infrared spectroscopy.