Show: 25 50 75 100 Results

Search results: 4 out of 4

استخدام المضمن الضوئي المكاني (SLM) كمفتاح بصري == Using the Spatial Light Modulator (SLM) as an Optical Switch

Author name: فرح غانم خالد العبيدي
Supervisor name: سمر يونس الدباغ | سؤدد سلمان البصام
General topic: Physics
Specific topic: Laser Physics and Electro-optics
Degree: Doctorate
University: University of Baghdad - College Of Science For Girls - Physics Department
Language: English
University location: Baghdad
First pages:

تصنيع كاشف من انابيب الكاربون النانوية لليزر الاشعة تحت الحمراء == Fabrication of Carbon Nanotubes Detector for IR Laser

Author name: مروة عبد الرحمن داود
Supervisor name: سمر يونس طه | وسن رشيد صالح
General topic: Physics
Specific topic: Laser Physics and Electro-optics
Degree: Master
University: University of Baghdad - College Of Science For Girls - Physics Department
Language: English
University location: Baghdad
First pages:
Abstract: في هذه الدراسة تم تصنيع كاشف يعمل في منطقه الاشعة تحت الحمراء البعيدة وبدرجة حرارة الغرفة باستخدام اربع انواع من انابيب الكاربون النانوية متعددة الجدران. (MWCNTs, COOH - MWCNTs, short - MWCNTs and DWCNTs) .انابيب الكاربون النانويه رسبت بتقنيه (dip coating) و((drop casting لتحضير اغشية انابيب الكاربون النانوية متعدد الجدران على قاعده سليكون مسامي من نوع n و. p تم تبخير اقطاب الالمنيوم على اغشيه انابيب الكاربون النانوية لتصنيع كاشف يعمل في منطقه الاشعة تحت الحمراء البعيده. تم دراسه الخواص التركيبيه والطبوغرافية والبصريه وحسابات هول لهذه الاغشيه المصنعة . تم فحص الخواص التركيبه لغشاءMWCNTs باستخدام حيود الاشعه السينيه (XRD) واظهرت النتائج ان له تركيب متعدد االتبلور وشكله سداسي والغالب كان باتجاه (002). مجهر القوة الذري ((AFM تم فية التركيز على تشخيص خواص السليكون المسامي مع انابيب الكاربون النانوية متعددة الجدران. وجد ان الفلم له توزيع سطح متجانس مما يشير الى التوزيع الجيد لانابيب الكاربون النانوية فوق النتؤات النانوية للسليكون. تم تعين معدل الحجم الحبيبي وكانت بحدود 87.05 nm . المجهر الالكتروني الماسح (SEM)استخدم لدراسة طوبوغرافية اغشيه انابيب الكاربون النانوية متعددة الجدران ووجد ان هذه الاغشيه متجانسة ولاتوجد فيها اية تكتلات او شقوق .فجوة الطاقه البصرية في المنطقة تحت الحمراء تم ايجادها من فحص FTIR وكانت فجوة الطاقة0.12 eV. دراسة طيف رامان ولانابيب الكاربون النانوية متعددة الجدران, بينت ان الطيف يتحدد بثلاثة انواع من الحزم D وG وPRM .وجدن الخط (D) وجد انه يقع عند 1561.62 cm - 1 والتي تشير الى عدم الانتظام بسبب العيوب وتقوس لشبيكه انابيب الكاربون متعددة الجدران بينما الخط (G) يقع بحدود 1750 cm - 1 ويكون نتيجه اهتزازات في اواصر C - C الخط الثالث PRMكانت تقع عن2700 cm - 1, هذه الحزم ممكن استخدامها لتقدير اي عيوب في الكاربون. نسبه الشدة D/G تساوي 1.135 . مطياف الاشعه تحت الحمراء استخدم لدراسة طيف انابيب الكاربون النانوية وللبوليمر والصبغة وظهرت امتصاصية جيده لانابيب الكاربون النانوية عند الطول الموجي 10.6 µm والذي يقع ضمن منطقة تحت الحمراء البعيدة ممايجعلها اختيار جيد لتطبيقات الاشعة تحت الحمراء. اظهرت قياسات تاثير هول ان انابيب الكاربون متعدد الجدران المرسبة على قاعدة السليكون المسامي هي من نوع شبه الموصل الموجب p - type)) ولها توصلية عالية. خصائص التيار - فولتيه واستجابيه الكاشف المصنع قيست عند الظلام والاضاءة لهذه الاغشيه بواسطه التشعيع بليزر ثاني اوكسيد الكاربون بطول موجي 10.6µm وبقدرة 2.5 W و2.2 . استجابية وخصائص كاشف التوصيل الضوئي تم تحسينها عن طريق تغطية افلام انابيب الكاربون النانوية متعدد الجدران بطبقة سمكها0.1mm من البوليمرات polyanilin وpoly methyl acrylae وبالاضافة الى صبغة methylene blue هذه الانواع من البوليمرات المطعمة بالصبغه تعتبر كمعالجة سطحية لغشاء الكاشف والتي تزيد بشدة من الاستجابيه الضوئيه لكاشف اشعه تحت الحمراء البعيدة.خصائص الكاشف (الكشفيه , الربح ,الاستجابه , القدره المكافئه للضوضاء ) حسبت قبل وبعد عملية الطلاء بالبوليمر ووجد ان الربح يزداد بحدود 25 مره اكثر من النماذج غير المطعمة .بينما الكشفيه ازدادت من (cm.Hz^1/2)/W 107 الى 1011(cm.Hz^1/2)/W بعد طلائها بالبوليمر .النتائج اظهرت ان الاستجابيه تزداد اكثر من الاستجابيه لاغشيه الكاربون النانوية غيرالمطعمه وتصل الى 0.0177 A/W لنوع انابيب الكاربون متعدد الجدران من نوع شبه الموصل السالب المحضر بطريقه (drop by drop ) وبينما اعلى الكشفية النوعيه بعد اضافه البوليمرات المطعمه بالصبغه كانت 7.08*1011 (cm.Hz^1/2)/W في حالة انابيب الكاربون متعدد الجدران لنوع شبه موصل السالب محضر بطريقه (dip coating) .هذه القيم تعطي اثبات لتاثير البوليمر في تحسين خصائص كاشف التوصيل الضوئي الاشعة تحت الحمراء البعيدة تم التحقق من تاثير تغطية اوتطعيم افلام انابيب الكاربون النانوية بالبوليمر على زمن الاستجابة الكاشف ووجد ان زمن النهوض كان 1.42ms , زمن الاستجابية كان 2.14ms بينمزامن الهبوط كان 3.92ms . | In this study the infrared photoconductive detectors works at far infrared region and at room temperature were fabricated. The detector fabricated using four types of carbon nanotubes CNTs (MWCNTs, COOH - MWCNTs, short - MWCNTs and DWCNTs).The carbon nontubes suspension is deposited by dip coating and drop - casting techniques to prepare thin films of CNTs. These films are grown on porous silicon (PSi) substrates of n - type and p - type Si. The aluminum electrodes were evaporated on the CNTs film to fabricate the far IR detectors.The structural, morphological, optical properties and Hall measurements of the film were studied. The structure of the MWCNTs film is examined by X - ray diffraction (XRD) and found to be polycrystalline of hexagonal structure with strong orientation at (002). The AFM studies are focused on the characterization of the PSi - CNTs and found it had a good and uniform surface homegensity which gives a good indicator for formation of the MWCNTs over the nanospikes of Si. The average particle size was determined and found to be 87.05 nm. The scanning electron microscope (SEM) technique has been applied to study the morphology of the deposited MWCNTs film. The results shows that the film are homogeneous and does not have areas with clusters or cracks.The optical energy gap in the IR region was calculated from FTIR spectrum and found to be 0.12 eV. From Raman shift spectrum for the MWCNTs, it was found that the spectrum is dominated by three typical lines; D - band, and G - band, and RPM band. The D - line is located about 1561.62 cm - 1 which assigned to the disorder induced by defects and curvature in the nanotube lattice, while G - line is located about 1750 cm - 1 due to the in - plane vibration of the C - C bonds. The RPM band is located at 2700 cm - 1 . These bands can be used to evaluate the extent of any carbon - containing defects. The D/G intensity ratio was 1.135. FTIR spectrophotometer was used to study the infrared spectrum of CNTs, polymers and Methylene Blue dye, which appear that CNTs have good absorbance in the wavelength of 10.6 µm. This is mean that these materials are very good candidate for IR applications. Hall Effect measurements show that the carbon nanotubes deposited on porous silicon substrate has a p - type semiconductor behavior and high conductivity. The I - V characteristics and the photoresponsivity of the fabricated detector are measured at dark and under illumination for CNTs film by IR radiation from CO2 laser of 10.6µm wavelength and power of 2.2 and 2.5W. The photoresponse and figures of merit of the photoconductive detector is improved by coating (functionalized) the CNTs films with layer of 0.1 mm of the blend polyaniline, polymethylmeth acrylate and methylene blue dye. This type of polymer coating can be considered as a surface treatment of the detector film, which highly increases the photoresponse and specific detectivity of the fabricated CNTs IR detector. The figure of mertis (Rλ, G, NEP and D*) were calculated before and after functionalization process. It is found that is increased in about 25 time than that for uncoated samples, while the specific detectivity was increased from order of 10+7 (cm.Hz1/2)/W to 10+11 (cm.Hz1/2)/W after coated with polymer.These values give an improve for the effect of polymer on the enhancement of the performance of IR photoconductive detector. The effects of the coating CNTs film with polymer on the response time of the detector investigated and found that the rise time was 1.428 ms, response time 2.14 ms while the fall time was 3.92ms .

تحضير جسيمات اوكسيد الخارصين النانوية الممزوجة بالحديد بطريقة الليزر النبضي == Synthesis of ZnO Nanoparticles Mixed with Fe Using Pulse Laser Deposition

Author name: ايمان عكيدي مكحول
Supervisor name: سمر يونس طه
General topic: Physics
Specific topic: Laser Physics and Electro-optics
Degree: Master
University: University of Baghdad - College Of Science For Girls - Physics Department
Language: English
University location: Baghdad
First pages:
Abstract: In this work, pulsed laser deposition (PLD) technique is employed to prepare pure ZnO and ZnO mixed with Fe thin film at different concentration on glass substrate. Nd.YAG laser beam, λ=1064 nm, repetition rate 6Hz with the pulse duration 10ns has been used to deposited ZnO and ZnO : Fe thin films under vacuum of 10 - 2mbar. The effects of the number of laser pulses (100,300,600 and 800), Fe concentration (3,5,7%wt) at ambient temperature and annealing temperature at 500ºC on the structure, optical and electrical properties of these films have been studied.The structure characteristic investigated by X - Ray Diffraction (XRD). XRD pattern showed that as number of laser pulses increase the structure changed from amorphous to polycrystalline at 800 laser pulses for pure ZnO. For ZnO : Fe(3%) the structure stay polycrystalline and the intensity increased also the grain size increase. Same result obtained as the concentration of Fe increased (3,5and 7%) for ZnO : Fe thin films and after annealing.The morphology is analyzed by AFM technique. The AFM results showed that the Root Mean Square (RMS) of surface roughness is increased with increasing number of laser pulses from 5.96 nm to7.16 nm and from 3.23nm to 10.2nm for both films of pure ZnO and ZnO : 3%Fe respectively. The RMS for both surfaces were increased at the pulses range 4.15nm to 8.55nm when increasing Fe concentration at ambient temperature and conducted by annealing process.The optical properties measured by UV - VIS spectrometer to compute the band gap of pure ZnO and ZnO : Fe were found high transparent in the visible region band gap for ZnO and ZnO : 3%Fe were decreased from 3.13 eV to 2.9eV and from 2.8eV to 2.55eV respectively. As well as the energy gap was found severe reducing in its values when the Fe increased, where the energy gap suffer decreased and became 3.02eV to 2.52 eV at ambient temperature and from 3.15 eV to 2.7eV after performed annealing process.The hall effect measurement proves that the pure ZnO and ZnO : Fe are n - type semiconductor, the conductivity is increased by increasing mixing Fe concentration where the value was increased from 6.4X10 - 4 Ω. - 1cm. - 1 to 6.37 Ω. - 1cm. - 1 and from 1.97X10 - 5 Ω. - 1cm. - 1 to 5.207 Ω. - 1cm. - 1 when achieved annealing at 500ºC.

تحضير جسيمات ثنائي اوكسيد التيتانيوم النانوية بطريقة الصول - جل باستخدام الازالة بالليزر وتطبيقاته كاصباغ نانوية == Synthesis of TiO2 Nanoparticles by Sol - Gel Method using Laser Ablation for Nano Paint Application

Author name: زينب ناصر جميل
Supervisor name: سمر يونس طه | عدوية جمعة حيدر
General topic: Physics
Specific topic: Laser Physics and Electro-optics
Degree: Doctorate
University: University of Baghdad - College Of Science For Girls - Physics Department
Language: English
University location: Baghdad
First pages:
Abstract: Titanium dioxide (TiO2) nanoparticles (NPs) have been widely investigated to employ in the paint fields due to its importance as pigments. Therefore, TiO2 particles are perfect candidates in the paint industry. In addition to use nanoparticles for enhancing the local coating properties in our country.In this work, the sol - gel technique employed to prepare TiO2 nanoparticles with two procedures and two precursors (TIP and TiCl4), the obtained two phases of TiO2 (anatase and rutile), nanopaticles colloid irradiated by pulse laser ablation (PLA) for minimizing particle size. It has been fabricated a laboratory paint (TiO2/SiO2 hybrid sol - gel). Nanoparticles characterization has been carried out by different devices to study properties such as morphology, structure and optical properties, Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS) demonstrated the size and shape of nanoparticles in the range of (3 - 40) nm spherical for anatase, while the rutile results were around (50 - 70) nm with ellipsoidal shape. Scanning Electron Microscopy (SEM), which was confirmed the results of TEM and DLS. Zeta - potential (ζ) results which were indicated the colloid stability, surface charge for the first procedure and the second procedure, anatse and rutile (+39.02, +25.68,+41.31 and+34.33) mV, respectively. The structural characteristics of TiO2 nano - powder investigated by X - ray Diffraction(XRD) to define the phases of TiO2, anatase at 500˚C , rutile at 900˚C, and Raman Spectroscopy to distinguish between crystalline phases, Raman shift resulted for anatase about (142.1,411.1,547.4 and 669.6) cm - 1, rutile (190,272,452 and 616) cm - 1. The optical properties measured by UV - Vis. Spectrophotometer to compute the energy band gap for both phases at (3.8 eV) for anatase and (3.4 eV) for rutile.The nanoparticles were mixed with coating solution (i.e. hybrid sol - gel and organosilicate nanoparticles (OSNP) in different concentrations (1%wt and 10%wt) for both anatase and rutile. Films were prepared by spin coating method which has been studied by the Energy Dispersive X - ray Spectroscopy (EDS) / Scanning Electron Microscope to define the components of concentrations, additionally, the films were studied the thickness and refractive index (n) by Spectroscopic Ellipsometry(SE) for nano - anatase (1%wt and10%wt) films thickness (128,382)nm and n equal (2.25,3.32), for nano - rutile films thickness (313.5,645.2) nm and n equal (2.5,2.8). Profilometer investigated the coating topography to demonstrate the Root Mean Square (RMS) toidentify the roughness which increased by increasing particle size. Fourier Transform Infrared (FTIR) analysis showed the strong bonds of the nanoparticles in frequency region between (400 - 1000) cm - 1 corresponds to Ti - O - Ti, also the bands at 793 and 1100cm - 1 were for a symmetric Si - O - Si stretching and vibration, respectively.Self - cleaning tests on the films were performed using Rhodamine B (RhB) as a pollution indicator. The effect of UV - irradiation on the films and contact angle measurements were studied. Anatase and rutile incorporated as a mixture with different ratios (1%.1.5% and 2%) in the local paint measurements, such as a washability and contrast test.Antibacterial activity in 10 - 5 and 10 - 3 TiO2 concentrations exhibited superior antibacterial activity with two types of bacteria, Escherichia coli (E - coli) and Staphylococcus aurous (S. aureus), respectively. TiO2 nanoparticles were more efficient as antibacterial agents with Staphylococcus aurous as compared with E - coli.