ATTI DELLA “FONDAZIONE GIORGIO RONCHI” ANNO LXVI, 2011 - N. 3 Structural and dispersion parameters of AgNO 3 embedded in PVA matrix NADIR FADHIL HABUBI (*), SAMI SALMAN CHIAD (*), RAMIZ A. MOHAMMED (**) SUMMARY. – AgNO 3 doped poly (vinyl alcohol) was prepared by casting technique, the characte- rization of PVA and AgNO 3 embedded in PVA matrix was confirmed by FTIR, optical absorption spectra were recorded in order to use the single oscillator model to clarify the dispersion parameters, the changes in dispersion were investigated as a function of AgNO 3 content. The optical energy gap decrease from 2 eV to 1.58 eV as the AgNO 3 content increased from 0% to 9%. Analysis revealed that the kind of transition is the direct allowed one. Key words: Polymers, casting method, dipersion parameters, optical energy gap. 1. Introduction In recent years great progress in understanding polymer surface phenomena and development in their theoretical aspects have been done. Forces occurring on polymer surfaces depend on the interaction between macromolecules, which are different inside the material and on the phase boundary (1). Poly (vinyl alcohol) (PVA) is one of the most polymeric materials as it has a unique properties such as, crystalline polymer, highly soluble in water, its disso- lution requires the breaking of the crystal structure and need to be carried out at elevated temperature (2,3), it possesses good hydrophilicity (4), one of the crucial features of the PVA consists in an existence of the promising acousto-optical ef- fects determined by interaction of electron and phonon subsystems (5). PVA has been widely used as a solid polymer electrolyte, solid state electro- chromic displays, solid state photocell (6-8), in ultrafiltration membrane (9), in (*) Al_Mustasiriyah University, College of Education, Physics Dept., Baghdad, Iraq, e- mails: nadirfadhil@yahoo.com, samichiad2003@yahoo.com. (**) Baghdad University, College of Science for Women, Physics Dept., Baghdad, Iraq.