Seminer: Positron Annihilation Spectroscopy: State-of-The-Art Technique to "See" Pores at the Atomic Level in Materials

Positron Annihilation Spectroscopy: State-of-The-Art Technique to "See" Pores at the Atomic Level in Materials

Tarih ve Yer: Fizik Bölümü Semineri; 04 Eylül 2013 Çarşamba Saat 14:00

Konuşmacı: Renwu John Zhang (Ph. D.), Department of Chemistry and Biochemistry, California State University, San Bernardino, USA

Özet: Positron annihilation spectroscopy, which is based of the quantum effect of positron and its bound state (called positronium), provides a unique way to study voids and free volume holes at atomic scale in various materials, such as metals, semi-conductors, and polymers.  It provides a non-destructive method to access the size and distribution of ultra micro-pores (~Å) and possible the chemical environment inside the pores as well in bulk materials.  By controlling the kinetic energy of incident positrons, the technique can also be used to study the surface voids and the voids at the interface between thin films and substrates.  In this talk, a brief introduction on this technique, including positron annihilation lifetime spectroscopy (PALS), Doppler broadening energy spectroscopy (DBES) and slow positron beam, and their major applications in material science will be presented. Two sample researches, characterizing free volume in polyamide thin films and studying the chemical environment in halogenated polystyrenes will be discussed.

İrtibat: Prof. Dr. Uğur Yahşi (uyahsi@marmara.edu.tr) ve Doç. Dr. Cumali Tav (ctav@marmara.edu.tr)

NOT: Bu Etkinlik TUBİTAK (2221-Konuk Bilim İnsanı Destekleme Programı) tarafından desteklenmektedir.

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