Study of Thin Films using Positronium Annihilation lifetime Spectroscopy

This project will use a Positronium Annihilation Lifetime Spectroscopy (PALS) technique to study a range of polymer nanocomposite samples supplied by collaborators at Columbia University.  The PALS technique uses a small (~10-50 micro-Ci) radioactive beta+ source to implant positrons (anti-electrons) into a target sample. The goals of this project are to gain an understanding of the PALS technique and its use to study a wide variety of materials that are of interest to industry or science. 

 

Student Tasks and Responsibilities: A typical student investigation can involve varying the fractional composition of the sample and studying temperature-induced and time-dependent (relaxation) variations in the measured lifetime; all as a measure of how pore volume changes in the sample under such conditions.  Fast timing techniques in nuclear science will be used. A controlled heating stage in the existing PALS system is operated by the student to study the glass transition of the polymer.  The student will perform a study of a series of polymer films that have been systematically altered.  Data fitting routines are used to analyze the data and the student will report results to the group as a whole.