Influence of Diethyl Phthalate (DEP) on Fluorescence Emission Quenching of Poly Vinyl Chloride (PVC) in Solid Films Esam Ahmed Tawfiq, Gada Mehdi Kamil and Hadeel Salah Mansour 1 Diyala Journal for Pure Science P-ISSN: 2222-8373 E-ISSN: 2518-9255 Volume: 16, Issue: 2, April 2020 Manuscript Code: 518C Influence of Diethyl Phthalate (DEP) on Fluorescence Emission Quenching of Poly Vinyl Chloride (PVC) in Solid Films Esam Ahmed Tawfiq* 1 , Gada Mehdi Kamil 2 and Hadeel Salah Mansour 2 1 Department of Applied Sciences – Branch of Applied Physics – University of Technology – Baghdad – Iraq 2 Department of Applied Sciences – Branch of Applied chemistry – University of Technology – Baghdad – Iraq * esamtawfiq123@gmail.com DOI: https://dx.doi.org/10.24237/djps.16.02.518C Received: 27 October 2019 Accepted: 18 December 2019 Abstract In this study, the effects of temperature on the absorption and emission spectra of polyvinyl chloride films were investigated in the presence of diethyl phthalate as a quencher. In this paper, diethyl phthalate (DEP) was used as a quencher at different concentrations to study its effect on the behavior of absorption and emission spectra in the wavelength range from 200 to 350 nm. The films have been treated thermally at 25, 40, 50 and 60 o C. The results showed that the absorption spectrum contains two absorption bands for all samples. The first absorption band appeared in the range of 200 to 220 nm. The maximum absorption band was shifted towards red wavelengths depending on the concentration and temperature. The second absorption band appeared from 260 to 300 nm was weak, broad and unaffected by a concentration while showing a simple response to temperature without displacement in the maximum absorption (λmax.). The changes in absorbance as a function of quencher concentration at room temperature (25 o C) are illustrated.