Influence of Gamma Radiation on Some Optical Properties and Urbach Energy of (PMMA- Doped Red Methyl) Films Hala Abd Alsahib Wadi Ministry of Education / General Directorate of Vocational Education /Training and Investment Division Received in : 6May 2013 Accepted in :24 September 2013 Abstract We have studied the effect of gamma irradiation on the optical transmission, absorbance, absorption coefficient, and Urbach energy for (PMMA- doped red methyl) film deposited by using solvent casting method .The optical transmission (T %) in the wavelength range (190- 1100 ) nm of films was measured , it was seen that all the parameters were affected by gamma irradiation. Key words : PMMA films , Optical properties , gamma radiation. 219 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 Introduction Poly (methyl methacrylate) PMMA has considerable attention in recent year owing to its low cost, good tensile strength, and hardness, high rigidity, transparency, low optical loss in the visible spectrum, low glass temperature, good insulation properties and thermal stability dependent on tactility, it can be considered as a good host for inorganic nanoparticle due to their high surface to bulk ratio which can significantly affect the properties of PMMA matrix [1-4], as a result of the above properties, PMMA has been extensively used in various industrial sectors, it is used as a substrate material for precision optics components, in memory, gas sensing, PMMA can be tailored chemically to fit awide range of photonics and optoelectronics applications, liquid crystal display [5-7]. Irradiation with X-rays, alpha, beta and gamma radiation also have a significant effect on polymer properties and some physical properties are usually modified [8]. Radiations by γ-rays change the physical properties of the materials the internal structure of the absorbed substances. Studies on the changes in optical properties of thin film irradiated with ionizing radiations yield valuable information regarding the electronic processes in these materials [9]. The aim of the present work is to study the effect of γ-irradiated on some optical properties and Urbach energy of of (PMMA- doped red methyl) films Experimental details Poly (methyl methacrylate) from (sigma Aldrich comblt Germany) , chloroform has purity of 99.8% (HPLC_ was used as a common solvent for both pure PMMA and (red methyl) were dissolved separately in chloroform for 4 hours at room temperature. Appropriate mixtures of PMMA and 8% weight (red methyl) solutions were mixed . The solution was poured into flat glass plate dishes. Homogenous films were obtained after drying the solution in an oven for 24 hours. The thickness of the prepared films was in the range of 25 ± 1 µm. the prepared samples were irradiated by gamma ray dose from (137Cs) with activity (0.5 µ Ci), for seven days. The irradiation facility is at the College of Science , University of Diyala . The absorbance and transmittance spectra were recorded by using double bean schimadzu UV/VIS-160A in the wavelength optical a range (190-1100) nm, the measurements were carried out at room temperature. Results and Discussion Figure (1) shows the variation of transmittance with wavelength for unirradiated (PMMA- doped red methyl) & Irradiated one. Transmittance for unirradiated film is higher than that for irradiated one, this might be attributed to the increased scattering of photons by crystal defects, and the free carrier absorption of photons contributed to the reduction in optical transmittance [10]. Figure (2) shows the absorptance of unirradiated & irradiated (PMMA- doped red methyl) films versus wave length from this figure the absorptance [irradiated (PMMA- doped red methyl)] > absorptance [unirradiated (PMMA- doped red methyl)]. The irradiated thin film shows a much softer absorption edge, possibly indicating the presence of sub-band gap levels associated with defects. The following relation could be used for calculating the absorption coefficient (α) [11]: ------------- (1) t A303.2 =α Where (A) is the absorptance and (t) is the film thickness. 220 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 Fig. (3) shows the dependence of the absorption coefficient (α) on the wave length for the samples. At short wavelength (α) takes higher value (α≥104) cm-1 and then increases with the decrease of λ (increasing photon energy). The Urbach relation as follows [12]: ------------- (2) α= α0ehυ/Ee Where (Ee) is the Urbach energy, (hν )is photon energy. Fig. (4) shows the relationship between ln(α) and photon energy. The value of (Ee) for (PMMA- doped red methyl) films of irradiated is (0.173 eV) and as deposited is (0. 182eV). The relatively high band tial values obtained in this work can be explained by the disorder present in the film. Conclusions The actions of irradiation by gamma ray on (PMMA- doped red methyl) films are: increasing the absorptance and absorption coefficient, and decreasing the transmittance and Urbach energy. The Urbach energy decreases from (0.182 eV) to (0. 173 eV). References 1. Gross ,S.; Di Noto ,V. and Schubert , U. (2003), Dielectric Investigation of Inorganic – Organic Hybrid Film Based on Zirconium Oxcluster – Crosslinked PMMA , Journal of Non – Crystalline Solids, 322, 154-159,2. 2. Tawansi , A.; El-Khodary , A.; Zidan , H. M. and Badr ,S. I. (2002), The Effect of MnCl2 Filler on the Optical Window and the Physical Properties of PMMA Films , Polymer Testing , 21:381-401,3. 3. Capan , I. ;Tarmci C.;Hassan , A. K. and Tanrisever , T., (2009), Characterisation and Optical Vapour Sensing Properties of PMMA Thin Films, Materials Sciene and Engineering C , 29:140-147. 4. Caseri , W. (2000) ,Nanocomposite of Polymers and metals or Semiconductors : Historical Baek Ground and Optical Properties , Macromolecular Rapid Communications , 21:705-712. 5. Klmberg-Sapieha , J. E.; Martinu, L.;Yamasaki, N. L. S. and Lantman ,C. W. (2005), Tailoring the Adhesion of Optical Flims on Poly Methyl-Methacrylate by Plasma-Induced Surface Stabilization , Jour. Thin Solid Films, 476, 01-107. 6. Beev , K. ; Temelkov , K.;Vuchkov , N.;Petrova, T.; Dragostinova ,V.;Stoycheva-Topalova , R.;Sainov , S. and Sabotinov, N. (2005), Optical Properties Of Polymer Films for Near UV Recording , Journal of Optoelectronics and Advanced Materials, 7 , 1315-1325. 7. X. M. Dong, Y. Luo, L. N. Xie, R. W. Fu and M. Q. Zhang, (2008) ,Conductive Carbon Black-Filled Poly Methacrylate Composites as Gas Sensing Materials: Effect Of Glass Transition Temperature , Journal of Thin Solid Films, 516, 7886-7892. 8. M.A. Khaled, F. Sharaf, M.S. Risk and M.M. El-Ocker, (1993), Effect of γ-irradiation on the refractive indices and optical absorption of Poly(Vinyl Alcohol) doped with NiCl2 and CrCl3, Polymer Degradation and stability, 40, 385. 9. Zhu,R.Y. , (1998), Radiation damage in scintillating crystals . Nuclear Instruments and Methods in Physics Research Section A: accelerators, Spectrometers , Ditectors and Associated Equipment ,413,297-311. 221 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 222 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 10. Ali Jasim AL-Jabiry ,(2007), PhD, thesis , University of Technology,Baghdad. 11. Han, X., Liu, R., Chen, W. and Xu, Z, (2008), Properties of nanocrystalline zinc oxide thin films , Journal of Thin Solid Films, 516, 4025- 4029. 12. Kasra Behzad, Wan Mahmood Mat Yunus, Zainal Abidin Talib, Azmi Zakaria and Afarin Bahrami (2012), Effect of Preparation Parameters on Physical, Thermal and Optical Properties of n-type Porous Silicon , International Journal of ELECTROCHEMICAL SCIENCE ,7 ,8266 – 8275. Figure No. (1) Optical transmittance of (PMMA- doped red methyl) before and after irradiation Figure No. (2) Absorptance of (PMMA- doped red methyl) before and after irradiation 223 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 Figure No. (3) The absorption coefficient of (PMMA- doped red methyl) before and after irradiation Figure No. (4) Relation between lnα and photon energy of(PMMA- doped red methyl) before and after irradiation بعض الخصائص البصریة وطاقة أورباخ ألغشیةتأثیر أشعة كاما في (PMMA- doped red methyl) ھالة عبد الصاحب وادي وزارة التربیة -المدیریة العامة للتعلیم المھني - قسم التدریب واالستثمار 2013ایلول 24قبل البحث في ، 2013ایلول 6استلم البحث في : لخالصةا وطاقة أورباخ ، معامل االمتصاصو البصریة ،واالمتصاصیة ، النفاذیة في أشعة كاماتم في ھذا البحث دراسة تأثیر األطوال قیست النفاذیة البصریة ضمن المدى. المحضرة بطریقة الصب (PMMA- doped red methyl) ألغشیة وجد أن جمیع المعلمات التي تمت دراستھا تأثرت بأشعة كاما .،ومن تحلیل ھذه األطیاف (1100nm-190)الموجیة أغشیة بولي مثیل میثاكریالیت، الخواص البصریة، أشعة كاما. الكلمات المفتاحیة : 224 | Physics @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹1a26@@ÖÜ»€a@I3@‚b«@H2013 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 26 (3) 2013 M.A. Khaled, F. Sharaf, M.S. Risk and M.M. El-Ocker, (1993), Effect of γ-irradiation on the refractive indices and optical absorption of Poly(Vinyl Alcohol) doped with NiCl2 and CrCl3, Polymer Degradation and stability, 40, 385.