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 .

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

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.

Radioactivity --- Dosimetry --- Thermo-luminescence --- TL --- SAM940 --- Flour --- Macaroni --- Basrah governorate