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Article
Dynamical Delay Normalize of Master Equations Model of
معايرة التأخير الدينامي لنموذج المعادلات الرئيسي لليزرات QD لشبه موصل

Author: R. M. Hassan, Prof.Dr. C. A. Emshary and Prof.Dr. S. I. Easa
Journal: Journal of Basrah Researches (Sciences) مجلة ابحاث البصرة ( العلميات) ISSN: 18172695 Year: 2011 Volume: 37 Issue: 1A Pages: 8-26
Publisher: Basrah University جامعة البصرة

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Abstract

By re-expressing of the master equations model of quantum dots (QDs) laser theory by C. Gies et.al (2007), we have added a dynamical delay factor to the s-shall population’s equations to take into account the retardation procedure. This addition has led to theoretical results nearly in isomorphism with experimental data . We present a theoretical simulation of characteristics and the turn-on dynamics of InGaAs/GaAs semiconductor QD laser output lasing with CW wavelength of 1.3μm at room-temperature including the photon-assisted polarization contribution.

من خلال إعادة صياغة نموذج المعادلات الرئيسي لنظرية ليزر النقاط الكمّية (QDs) للباحثين C. Gies و مشاركيه(2007) , أضفنا عامل تأخير دينامي إلى معادلات تعدادات طبقة - s ليأخذ في الحسبان إجراء التأخر. هذه الإضافة أدّت إلى نتائج نظرية تقارب البيانات التجريبية تقريبا.في هذا البحث نقدّم محاكاة نظرية لخصائص و ديناميكات بدء التشغيل لليزر QD لشبه موصل GaAs / InGaAs يعمل CW بطول الموجة من mm 1.3 في درجة الحرارة الغرف مع تضمين مساهمة الإستقطاب بمساعدة الفوتون.


Article
Morphological and Optical Properties of CdS Quantum Dots Synthesized with different pH values
الخواص المورفولوجية والبصرية لكبريتيد الكادميوم نقاط كمية المحضرة بقيم مختلفة من الاس الهيدروجيني

Authors: Akeel M. Kadim عقيل مهدي كاظم --- Wasan R. Saleh وسن رشيد صالح
Journal: Iraqi Journal of Science المجلة العراقية للعلوم ISSN: 00672904/23121637 Year: 2017 Volume: 58 Issue: 3A Pages: 1207-1213
Publisher: Baghdad University جامعة بغداد

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Abstract

Quantum dots (QDs) of cadmium sulfide (CdS) was prepared by chemical reaction method with different potential of hydrogen (pH) values. The morphological and optical measurements of cadmium sulfide QDs were considered by atomic force microscopy (AFM), ultraviolet-visible (UV-VIS.) and photoluminescence (PL) spectrometer respectively. The energy gap (Eg) was calculated from photoluminescence spectra were found to be about 2.7, 2.6 and 2.5 eV at pH values 8, 10 and 12 respectively for CdS QDs. The decreasing of energy gaps is rises from the effect the pH solution increases, which in turn leads to the shifted of the PL spectrum toward red shifted, which creates the energy bands at surface states are shallow bands. Fabrication of EL-device from CdS QDs with pH=8 was effective in efficient white light generation and intensity.

تم تحضير نقاط كمية من كبريتيد الكادميوم بطريقة كيميائية بقيم مختلفة من الاس الهيدروجيني. شُخصت الخواص المورفولوجية والبصرية للنقاط كمية من كبريتيد الكادميوم بواسطة مجهر القوة الذري و مطياف الاشعة الفوق البنفسجية-المرئية و الانبعاثية على التوالي. تم حساب فجوات الطاقة من طيف الانبعاث وقيمها كانت 2,7 و 2,6 و 2,5 الكترون-فولط لقيم الاس الهيدروجيني 8 و 10 و 12 على التوالي للنقاط كمية من كبريتيد الكادميوم. هذا النقصان بقيم فجوات الطاقة ناشئ من زيادة تأثير الاس الهيدروجيني للمحلول, الذي يؤدي بدوره الى ازاحة طيف الانبعاث نحو المنطقة الحمراء من الطول الموجي مما يجعل حزم الطاقة في الحالات السطحية هي نطاقات ضحلة. تم تصميم نبيطة الانارة من النقاط كمية لكبريتيد الكادميوم مع الاس الهيدروجيني 8 والذي يؤثر بشكل فعال على كفاءة وشدة الضوء الابيض الناتج .

Keywords

Quantum dots --- CdS --- Luminescence --- pH


Article
Preparation and Characterization of Y2O3, Sio2 Doped By Eu2O3 as Luminescent Ink

Authors: Abdulrahman Saleh Ibrahim --- Amel Salih Merzah
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2015 Volume: 16 Issue: 2 Pages: 45-52
Publisher: Baghdad University جامعة بغداد

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Abstract

This article includes the preparation of luminescence materials from rare earth (Eu ) ion doping Yttrium Oxide (Y2O3) 70% and SiO2 25% and study the characteristics of phosphors for ultraviolet to visible conversion. The phosphor materials have been synthesized by two steps: Preparing the powder by solid state method using Y2O3, SiO2 and Eu2O3 with doping materials concentration (70%, 25% and 5%) respectively and different calcination temperature (1000, 1200 and 1400 oC). The second step is to prepare the colloid solution by dispersing the produced powder in a polyvinyl alcohol solution (4%) .Powder preparation is achieved by mixing the powder according to weight percentage, milling by a ball mill using yttrium stabilized zirconia with the aid of propanol for homogenization then calcination the mixture at the above temperatures. The produced powder was characterized by X-Ray diffraction. Colloid preparation is achieved by dissolving the PVA in water (4%) then dispersing the powder into the solution by using the hot plate magnetic stirrer and ultrasonic bath. The produced powder was characterized by using Fourier transform infrared (FTIR) and Photoluminescence spectra (PL).The results of photoluminescence spectra show that samples were emitting red color with wave length of 612nm. The intensity of emission was increased with increasing calcination temperature.


Article
Measurement of Radioactivity in Flour and Macaroni Consumed in Basrah Governorate, Iraq and Evaluation of Gamma Dose Rates, Radiological Hazard Indices, Excess Life Time Cancer Risk and Ingestion Effective Dose

Authors: Abdalrahman Alsalihi1, --- Ali A. Abbas --- Riyadh Abualhail
Journal: Journal of Basrah Researches (Sciences) مجلة ابحاث البصرة ( العلميات) ISSN: 18172695 Year: 2017 Volume: 43 Issue: 2A Pages: 58-69
Publisher: Basrah University جامعة البصرة

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Abstract

The radioactivity levels of238U, 232Th, 40K and 137Cs were determined in 17brands offlour (6 brands) and macaroni(11 brands) consumed in Basrah, Iraq.This papershowed a comparison of the gamma absorbed dose rates (D),annual effective dose equivalent (AEDE)and the excess lifetime cancer risk (ELCR)for various types offlour and macaroni measured by SAM940-2G operating with BNC 2ʺx2ʺ gamma-ray NaI(Tl) detector along withthe thermoluminescencetechnique. For flour samples, the minimum specific activity values of 238U, 232Th, 40Kand 137Cs were 0.238±0.002 Bq/kg (at sample F1), 0.117±0.001 Bq/kg(at sample F4), 3.529±0.001 Bq/kg(at sample F4) and 0.040±0.007 Bq/kg(at sample F3) respectively, while the maximum values of the same isotopes were 0.325±0.002 Bq/kg(at sample F3),1.469±0.002 Bq/kg(at sample F5),102.348±0.001 Bq/kg(at sample F6) and0.179±0.003 Bq/kg(at sample F2) respectively. For macaroni samples, the minimum specific activity values of 238U, 232Th, 40Kand 137Cs were 0.195±0.002 Bq/kg(at sample M2),0.029±0.004 Bq/kg(at sample M1),40.390±0.001 Bq/kg(at sample M6)and0.01±0.008 Bq/kg(at sample M11)whereas the maximum values of the same isotopes were 1.430±0.002 Bq/kg(at sample M3),2.629±0.002 Bq/kg(at sample M11),294.495±0.001 Bq/kg(at sample M10) and0.566±0.002 Bq/kg(at sample M4).Various radiation hazard indices including the radium equivalent activity (Raeq), the ingestion effective dose (HT,r), the internal hazard index (Hin), the external hazard index (Hex), the gamma index (Iγ) andthe alpha index (Iα) have been determined for all 17 samples. Allachieved results have been found to be undertheinternationallimit standards. Thus, selected flour and macaronitypes are safe to be consumed in Basrah governorate. The findings of thisstudycould be used as a first step to create radiological baseline data of the hazard radiation in basic foodstuffsconsumed in Basrah/Iraq.

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