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خصائص نقل الالكترون العابر لانظمة نقاط كمية متعددة == Transient Electron Transport Properties of Multiple Quantum Dots Systems

Author name: حسه ابراهيم عسكر
Supervisor name: شاكر ابراهيم عيسى
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University Of Basrah - College Of Education For Pure Sciences - Department Of Laser Physics
Language: Arabic
University location: Basrah
First pages:
Abstract: We presented a theoretical study for the electron transportcharacteristic, within a system of multi - quantum dots coupled tothe three metallic leads (right lead as an electron reservoir andtwo left leads as an electron source). We take into account twoarrangements for the scattering regions, one composed of twoquantum dots and the other is composed of four quantum dots.The study concentrated on the system parameters that has itseffect on the characteristic of the electron transfer process andhow these characteristic are affect by the number of the quantumdots in the scattering region in the both arrangements for thescattering regions.The theoretical formulism depends on the one - electron model.Where, we assigning a single effective level for each quantumdots and by taking the effects of the leads continuum levels intoaccount which are show within the wide band gap approximationto produce an imaginary quantity add to the energy levels of thequantum dots, representing the broadening in each effectivelevels.The related basic equation of motion for all the correspondinglevels eigen function probability amplitudes are solvedanalytically by using Laplace transform technique. We calculatethe occupation probability for the right lead, the instantaneouscurrent and the average instantaneous current that passes throughthe right lead.Our calculated results for the time - dependent dynamical electrontransfer offered a general features that takes into account thefollowing effects :  Energy levels position changes with respect to the leadFermi level. A suitable applied bais voltage on the right and left leads. Changes of the coupling amount among the quantum dots levels and in between them and the leads levels. Change of the leads temperatureThe characteristic of the time - dependent charge transport in the system are shown through the relation between the average instantaneous current passes the right lead and the applied baisvoltage, which we show as follow :  For the case of the scattering region arrangement that compose of two quantum dots it is an Ohmic behavior. For the case of the scattering region arrangement that compose of four quantum dots it is a non - linear (non - Ohmic) behavior.

دور تذبذب الجسر في نقل الالكترون خلال نظام مانح - جسر - قابل == THE ROLE OF BRIDGE VIBRATION ON ELECTRON TRANSFER THROUGH DONOR - BRIDGE - ACCEPTOR SYSTEMS

Author name: بهاء علي طالب
Supervisor name: شاكر ابراهيم عيسى
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University Of Basrah - College Of Education For Pure Sciences
Language: Arabic
University location: Basrah
First pages:
Abstract: موضوع الرسالة هو دراسة تاثير اهتزاز الجسر وتكوين البولارون الصغير على عملية انتقال الشحنة بين المانح والقابل في الانظمة الجسرية الجزيئية. ولهذا الغرض تعاملنا مع اقتران الكترون - فونون قوي. واستخدمنا لهذا الغرض معادلات الحركة لسعات الدوال الكمية للنظام الجسري مع معادلة نمط الاهتزاز الديناميكي الكلاسيكي للجسر. بخصوص التعامل مع تقريب الحالة المستقرة والتقريب الساكن تم اعطاء صيغة لحساب طاقة البولارون وتقدير تاثيرها على عملية انتقال الشحنة الديناميكية بين المانح والقابل وبارامترات النظام التي تؤثر فيها. اذ لاحظنا ان الصفة العامة في منحنيات احتماليات الملء يكون اعتمادها على طاقة الجسر المؤثرة |∆(u)| اذ بزيادتها تقل احتمالية ملء مستوى الجسر ويقل عدد التذبذبات. ان وصفنا عملية منح البولارون بواسطة نظرية البولارون الصغير طورت لوصف الترابط القوي بين الالكترون والاهتزاز ضمن مفهوم البولارون الصغير، اي ان كل جسر يمكن ان يتذبذب (شبه) غير معتمد على تذبذب جيرانه من الجسور، او كل موقع جزيئي يتذبذب غير معتمد على تذبذب موقع جزيئي اخر. فضلنا المعالجة العددية في حل المعادلات والابتعاد عن الحل المستقر وتم حل معادلة النمط الاهتزاز الكلاسيكي حلا تحليليا بحيث يكون تاثير ترابط الكترون - فونون واضحا من خلال جعل مستوى طاقة الجسر معتمد على الزمن ويكون مسيطرا على احتمالية ملء مستوى الجسر. كما ان تاثير مستويات الطاقة المستمرة للقطبين المعدنيين على كل من مستويي المانح والقابل قد اخذ بنظر الاعتبار. وكان واضحا ان احتماليات ملء المستويات تضمحل بمرور الزمن وتتضاءل سعات التذبذب في المنحنيات، وان احتمالية ملء مستوى القابل هي الاكثر تاثرا بزيادة التعريض في المستويات. وايضا لاحظنا ارتباط تصرف احتمالية ملء مستوي الجسر مع تصرف احتمالية ملء مستوى المانح وذلك لان مستوى المانح هو مصدر الالكترون لتكوين البولارون مع الجسر.V وطبقت الصيغ الرياضية على عملية انتقال الشحنة خلال جزيئة الـ DNA. اذ تعاملنا مع نظام جسري ذي جزيئة اساس واحدة ونظام جسري ذي جزيئتين من الجزيئات المتسلسلة خطيا من جزيئات الحامض النووي الـDNA. اذ لاحظنا وجود اختلاف بسيط في احتماليات ملء المستويات بوجود القاعدة G/C او القاعدة T/A، او بوجود قاعدتين جزيئيتين، اذ لاحظنا ان التصرف الهام في منحنى احتماليات الملء هو عند زيادة ترابط الكترون - فونون نلاحظ تاثير تصرف منحنى احتمالية ملء مستوى مصدر الالكترون (المانح) على تصرف منحنى احتمالية ملء مستوى الجسر الاول (القاعدة الجزيئية الاولى) التي تكون على ترابط مع المانح وذلك لحدوث تشكيل البولارون الاول. بينما يكون تصرف منحنى احتمالية ملء مستوى الجسر الثاني مع تلك للجسر الاول غير متطابق بالتصرف وذلك بسبب ضعف اصرة الترابط بينهما. ويكون تصرف احتمالية ملء القاعدة الجزيئية الثانية مترابطا مع تصرف منحنى احتمالية ملء مستوي القابل وذلك لشدة الاصرة بين مستوياتهما. | The subject of thesis is the effect of bridge vibration and small polaron formation on the electron transfer (ET) in D - B - A system. For this purpose, we dealt with strong electron - phonon coupling. And we used for this purpose the equations of motion for quantum amplitudes and the equation of classical - dynamical vibration mode of the bridge system. For the case of steady state approximation and static approximation we gave a formula to calculate the polaron energy and estimate its effect on the dynamical ET between the donor and accepter and the parameters involved. where we note that the general feature of the occupation probability curves are depend on the bridge effective energy |∆(u)|, when it increases, the occupation probability and the number of vibration decreases. The description of polaron hopping by the theory of small polaron was developed to describe the strong coupling between the electron and vibration within the concept of small polaron, i.e. every bridge vibrates (semi) independently from neighboring bridges. we preferred the numerical treatment in solving the equations and get away from the static solution, we solved the equation of classical - vibrational mode analytically such that the effect of electron - phonon coupling became obvious by putting the bridge state in a time - dependent form, and controlling the occupation probabilities of the bridge. The effects of the continuous energy levels of the metlic electrodes on the donor and acceptor states is taken into account. And it was obvious that the occupation probabilities of levels vanish in time and so as the amplitudes of vibration, and the most obvious effect of continuous levels of electrodes is on acceptor state, also we note that the behavior of the bridge state occupation probability is related with the occupation probability behavior of the donor state, since the donor state is the source of electron for polaron formation in bridge site.We applied the mathematical formulae on charge transfer through DNA molecule. Where we dealt with bridge system as a single base molecule or two liner consecutive molecules bases of DNA molecules. Where we note there is a small difference in occupation probabilities of G/C base or T/A base or between that of two bases. The important feature in occupation probabilities curves is that when electron - phonon coupling increases, we note that the effect of the occupation probability behavior curve for donor state on the occupation probability behavior curve of the first bridge which is connected with the donor because of the formation of the first polaron, while the behavior of the occupation probability of the second bridge and that of the first bridge is not coincide because of the weak interaction between them, but the occupation probability behavior of the second bridge state is related with that of the acceptor because of the strong interaction between them

خصائص نقل الالكترون لكيوبت مقترن بترانزستور الالكترون المفرد == The Electron Transport Properties of Qubit Coupled with SET

Author name: ايات طاهر ابراهيم
Supervisor name: جنان مجيد المخ
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University Of Basrah - College Of Education For Pure Sciences - Department Of Laser Physics
Language: Arabic
University location: Basrah
First pages:
Abstract: In this work, the dynamics of electron transport through a system consists of qubit (two coupled quantum dots) electrostatically coupled with single - electron transistor (quantum dot coupled to leads). The time - dependent Hamiltonian, that is used to describe the system energy, includes the electrostatic coupling between the qubit and the single - electron transistor. The time - dependent equations of motion for all the creation and annihilation operators are expressed in Heisenberg representation to derive the differential equations of motion for the quantum dots occupation numbers of the qubit and the single electron transistor, the related equations of motion for the correlation functions and also the formula that calculates the current which tunnels from the left lead to the single - electron transistor quantum dot. The system of equations of motion are treated by using the wide band approximation, and are solved numerically by using six order Runge - Kutta method, where the error is calculated at each step of time. By getting use of the system of differential equations solutions, the qubit and the single - electron transistor quantum dots occupation numbers are calculated as a function of time, in addition to the current that tunnels from the left lead to the single electron transistor quantum dot as a function of time.The main goal of this study in to investigate the effect of the parameters that related to the qubit and the single - electron transistor and their role in determing the electron transport process features through the whole system. These parameters, that are related to the initialization, manipulation and measurement processes, are the qubit and the single electron transistor quantum dots energy levels, the coupling strength between the qubit quantum dots, the electrostatic coupling between thequbit and the single electron transistor in addition to the coupling strength between the single - electron transistor quantum dot and the leads as well as the leads properties such as tempreture and band width. The effects of quantum dots energy levels tuning and the symmetry of the coupling with leads on the electron transport through the system are also investigated.Our study highlights four important physical features that related to the initialization, manipulation and measurement processes, these are : 1. The occupation numbers of the quantum dots of the qubit and the single electron transistor and the current of SET at the final time of measurement.2. The charge accumulation on the qubit quantum dots, at the final time of measurement, on the far - removed quantum dot and the nearest one to the single - electron transistor, that can be controlled by appling bias voltage and gate voltage.3. The determination of the time - current dependence if it follows the dependence of the far - removed or the nearest qubit quantum dot occupation number on time.4. The role of qubit energy levels tunning and the asymmetric coupling with the leads in determining the suitable initialization and manipulation processes get the quantum measurement with high quantum efficiency.

اللااستقراريات والفوضى في الدوائر الالكترونية

Author name: ابو طالب يوسف عباس عبد الكريم الشامي
Supervisor name: نوري حسين نور الهاشمي | فرات احمد مهدي السيمري
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University Of Basrah - College Of Education For Pure Sciences - Department Of Laser Physics
Language: Arabic
University location: Basrah
First pages:

التراكيب الالكتروني بعض المعقدات المعدنية المختارة

Author name: فائق عبد الله محمد التميمي
Supervisor name: حامد ابراهيم عبود محمد التميمي
General topic: Physics
Specific topic: Electronics Physics
Degree: Doctorate
University: University of Babylon - College Of Science - Physics Department
Language: English
University location: Babylon
First pages:
Abstract: The aim of the present work entitled " Electronic Structure of SomeSelected Metal Complexes " is to present a theoretical study based on thehybrid function of three parameters Lee - Yang - Parr B3LYP of the densityfunctional theory DFT quantum mechanical approach together with theStuttgart Dresden triple zeta SDD basis sets. All calculations are carried outby employing the used method at the Gaussian 09 package of programs.The studied metal complexes are twenty four divided into three groups : Platinum metal complexes, Vanadium metal complexes and Aluminummetal complexes. The electronic structure of the complexes includes thestructural, electronic, spectroscopic and excitation states properties.The results show that the SDD basis sets are efficient stronglysuggested for heavy metals and give good relax for the structures of thestudied metal complexes, where the geometrical parameters for cis - platinare in a good agreement with experimental results. Cis - platin has a largeabsolute value of chemical potential with low value of electrophilic index.Cis - platin has high ability to chemically interact with big molecules and ittakes place either in a clinical use or under clinical trials. Some platinummetal complexes and compounds have high symmetric distribution ofelectron density and electrostatic potential and others make variousbehaviors for electron transfer. Platinum metal complex isomers have thesame behavior of platinum centered compounds such as carboplatine andoxaliplatin used as drugs in clinical uses, where the ammine or bidentateammine ligands and either chlorides or carboxylate are leaving groups.The platinum metal complexes have high ability to interact with largemolecules due to their symmetric in the space and to participate either inclinical use or under clinical trials as agents. All platinum metal complexcompounds have electrophilic index greater than that for cis - platin and theyIIare soft compounds, they can easily interact with big soft molecules suchas enzymes or DeoxyriboNucleic Acid DNA.The results state that the vanadium metal complexes have low LUMOHOMOenergy gap and they are more biological activity. Moreover, theoxygen and chlorine atoms in vanadium metal complexes have an ability tointeract with the receptor reactive sites. The results of quantum chemicalparameters indicate that the vanadium metal complexes are soft and caneasily interact with enzymes. The results of nuclear magnetic resonancecalculations illustrate the central vanadium metal ion in all complexes thathave the lowest value of magnetic shielding and chlorine atoms whosemagnetic shielding values depend on the coordination for each complex.The molecular polarizability calculations showed that the vanadium metalcomplexes have chemical activity and high ability to interact with speciesespecially the enzymes in which they are soft big molecules. For aluminum metal complexes, the results reinforce that they have various electronic applications with different LUMO - HOMO energy gaps.The differences of the HOMOs and LUMOs energies distribution make the aluminum metal complexes to have chemical reactivity as Ziegler - Natta catalysts in the chemical applications such as polymerization processes.The results also prove that the electron density distribution is made from the aluminum metal complexes to have low electrophilic index in which they play a significant role as catalysts in many chemical reactions especially the polymerization processes.

حسابات عوامل التشكل النووية للاستطارة الالكترونية مع انموذج الفضاء الموسع sdpf لبعض النوى الخفيفة == Electron Scattering Form Factors Calculations with Extended sdpf Model Space for Some Light Nuclei

Author name: شامل راضي صاحب
Supervisor name: خالد صالح جاسم
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University of Babylon - College Of Education For Pure Sciences - Physics Department
Language: English
University location: Babylon
First pages:
Abstract: The energy levels of 17,18O, 19F, 20Ne, 25,26Mg and 27Al nuclei have been calculated with the extended sdpf - model space . The calculations are performed with sdpfnow as effective interaction. There is good agreement between theoretical and experimental levels for most states. This study confirmed many levels in the 25,26Mg and 27Al nuclei Theoretically. Nuclear structure of the above nuclei except 26Mg have been studied by the elastic and inelastic electron scattering to calculate the form factors and reduced transition probabilities over the momentum transfer range (0 ≤q≤3) fm^( - 1). The wave functions for this nucleus have been utilized from the shell model using sdpfnow as a two - body effective interaction. The wave functions of the single - particle matrix elements were calculated by the Harmonic Oscillator (HO) and Skyrme (SK) potentials. The charge density distribution was calculated using the HO, Woods - Saxon (WS) and SK potentials for the 18O, 19F and 20Ne nucleus.The Core - polarization (CP) effects are used by adopting the shape of the Tassie - Model (TM) and effective charges, the effective charges employed for all states are 0.35 for each of proton and neutron except for 17,18O are 0.65.Two shell model codes NuShellX@MSU and NuShell@MSU for windows have been used in this study. The form factors for most nuclei under consideration give a good agreements compared with the experimental data. The calculations of effective charge model give a good agreement in the first maximum of momentum transfer regions (q) in all the nucleus except 17,18O, where it failed in describing the longitudinal form factors. The CP effects with TM give a good agreement for the two maximum of momentum transfer regions and it is better than the effective charge model for all the nuclei except C2〖(1/2〗_1^+ 1⁄(2)) state in the 27Al nucleus, where the effective charge model seems to agree more with the experimental data compared with TM.Transverse magnetic form factors calculations of 〖3/2〗_1^+ 1/2 state in the 19F nucleus are performed by adjusting the g - factors to be 8.2, - 2.1 for the proton and neutron, respectively, calculations of the 〖9/2〗_1^+ 1/2 state in the 19F nucleus also performed by adjusting the g - factors to be 6.58, - 2.82 for the proton and neutron, respectively. The comparison between fp and sdpf - models space have been performed with fpd6 and sdpfnow effective interactions, respectively, for the 54Cr and 54,56Fe nucleus

تاثير الفلور على الخواص التركيبية الالكترونية والكهربائية لشريط الكرافين باستخدام النموذج الهاملتوني الرياضي == The Effect of Fluorine on the Structural, Electronic and Electrical Properties of Graphene Sheet by Using the Mathematical Hamiltonian Model

Author name: حكيمة سلمان جبر مرشد
Supervisor name: حامد ابراهيم عبود محمد التميمي
General topic: Physics
Specific topic: Electronics Physics
Degree: Doctorate
University: University of Babylon - College Of Science - Physics Department
Language: English
University location: Babylon
First pages:
Abstract: هذه الاطروحة دراسة نظرية للخواص التركيبية, الالكترونية والكهربائية لشريحة الكرافين النقي باستعمال النموذج الهاملتوني الرياضي, وتحديد تاثير عدد مختلف من ذرات الفلور المضافة بدلا من ذرات الكاربون في الشريحة على تلك الخواص. ابتداءا تم الحصول على استرخاء للتراكيب المدروسة بتطبيق الدالة الهجينة ذات المعاملات الثلاث لي - يانغ - بار من نظرية دالة الكثافة في حزمة برامج كاوس 09 تم الحصول على استرخاء التراكيب بتطبيق تقريب الكثافة الموضعية في برنامج .SIESTA trunk - 462 ان جميع حسابات الخواص الكهربائية تم اجراؤها باستعمال برنامج .Gollum وتم الحصول على استرخاء جيد للتراكيب المدروسة, حيث ان قيم الزوايا C - C, C - C=C ,C=C في شريحة الكرافين النقية تتفق مع تلك في تراكيب الحلقات الكاربونية. ان اضافة ذرات الفلور بدلا من ذرات الكاربون لتشكيل الشرائح المطعمة ليس له تاثير واضح على تلك الزوايا مع ملاحظة التفاف طفيف في حلقات الفينيل عند مناطق الارتباط مع الحلقات المطعمة والتي سببهزاوايا انحناء بين الذرات المختلفة نتيجة لاختلاف الكتل الذرية والكهروسالبية لذرات الفلور والكاربون. تبين النتائج ان الطاقة الكلية لشرائح الكرافين المدروسة تتناقص مع زيادة العدد الكلي للالكترونات في الشريحة, ان الطاقة الكلية هي انعكاس لطاقة الترابط لكل شريحة. ان فجوة الطاقة المحسوبة نظريا لشريحة الكرافين النقية هي فجوة طاقة صفرية, وان جميع الشرائح المطعمة تمتلك فجوة طاقة صغيرة مع عدم وجود اي قاعدة لخفض او ارتفاع فجوة الطاقة مع زيادة عدد ذرات الفلور في الشريحة. ان حسابات المدار الجزيئي العلوي المشغول والمدار الجزيئي السفلي غير المشغول تبين ان طاقات المدار الجزيئي السفلي غير المشغول هي اعلى من طاقات المدار الجزيئي العلوي المشغول وهذا يعطي هذه التراكيب المدروسة ان تمتلك قابلية عالية لنقل الالكترون. كما ان طاقة المدار الجزيئي العلوي المشغول تزداد خطيا مع زيادة عدد ذرات الفلور في الشريحة. وبينت النتائج ان شريحة الكرافين النقي تمتلك قيم كبيرة للتوصيلية الكهربائية والحرارية مقارنة مع الشرائح المطعمة وذلك لكون الكرافين النقي يمتلك قنوات مفتوحة متعددة لنقل الالكترون, هذه القنوات تتناقص خطيا مع زيادة عدد ذرات الفلور في الشريحة. لقد لاحظنا ان شريحة الكرافين النقي هي اكثر مرونة من الشرائح المطعمة نتيجة العدد المحدد من الحالات والناشئ من كثافة الحالات غير الصفرية لشريحة الكرافين النقية, وهذا ياتي نتيجة للاختلاف في الاتحاد الخطي للمدارات الذرية لتشكيل مدارات جزيئية في كل من الشريحة النقية والشرائح المطعمة. ان شريحة الكرافين النقي تمتلك معامل انتقال قيمته واحد نتيجة لعدم وجود منطقة استطارة في شريحة الكرافين النقي, ان جميع موجة الالكترون الساقطة سوف تنتقل من القطب الايسر الى القطب الايمن, وان اضافة ذرات الفلور سيقود الى ظهور مساحات كمناطق استطارة تخفض معامل انتقال الالكترون. في الدراسة الحالية, تم تحليل قياسات تيار - فولتية للشرائح النقية والمطعمة, لقد لاحظنا ان شريحة الكرافين النقية تبين مميزات تيار - فولتية مشابهة بشكل كبير الى نوع الممانعة, وان هذا السلوك لمثل هذا التركيب النانوي يخفض تماما تاثيرات الحرارة العالية التي تظهر في الاجهزة الماكروية. ان الشرائح المطعمة تمتلك تقريبا منحني تيار - فولتية مشابهة بالسلوك الى الشريحة النقية مع استجابة واطئة للتيار المقابل لفولتية الانحياز الامامي والعكسي. | This dissertation is a theoretical study of structural, electronic and electrical properties of pure graphene sheets using a mathematical Hamiltonian model, and determine the effect of various number of fluorine atoms added in place of carbon atoms in the sheet on these properties. The studied structures are initially relaxed by employing the hybrid functional three parameter Lee - Yang - Parr B3LYP density functional theory at Gaussian 09 package of programs, and then the structures are relaxed by employing the local density approximation LDA/Single Zeta SZ at the SIESTA - trunk - 462 program. All calculations of electrical properties are carried out using Gollum program. The results showed good relaxation obtained for the studied structures, the values angles C - C, C=C and C - C=C in pure graphene sheet are agree with those for carbon rings structures. Adding the fluorine atoms in place of carbon atoms to form the doped sheets has not significant effect on these bonds with few screw observed in phenyl rings at the contact areas with the doped rings comes from the twist angles between different atoms due to the difference of atomic mass and electronegativity of fluorine and carbon atoms. The results showed the total energy of the studied graphene sheets was decreased with increasing the total number of electrons in the sheet, total energy is a reflection of, binding energy of each sheet. The LUMO - HOMO energy gap calculated theoretically for pure graphene sheet is zero energy gap, and the other doped sheets all have small energy gap with no role of reducing or raising the energy gap with increasing the number of fluorine atoms in the sheet. The calculations of HOMO and LUMO showed LUMO energies are greater than the HOMO energies and this gave these studied structures to have high ability to electron transfer. Also, the HOMO energy is linearly increasing with increase of the number of fluorine atoms in the sheet. The results showed the pure graphene sheet has the greater values of electrical and thermal conductivity than those for doped sheets due to that the pure graphene sheet has multi open channels for electron transfer, these channels are linearly reducing with increasing the number of fluorine atoms in the sheet . Observed the pure graphene sheet is more solvability than the doped sheets due to a finite number of states from the non - zero density of states for pure graphene sheet, this comes according to the difference in the linear combination of atomic orbitals to form the molecular orbital in both pure and doped sheets . Pure graphene sheet has transmission coefficient is unity due to absent of the scattering regions in pure graphene sheet. All incident electron wave function was transmitted from left electrode to right electrode, adding fluorine atoms leads to appearing areas as scattering regions reduces the electron transmission coefficient. In present study, the I - V measurements were analyzed for pure and doped sheets, observed the pure graphene sheet show I - V characteristics very much similar to resisting type, this behavior of such nano - structure material completely reduces the high temperature effect that appeared in the old macro devices. Doped sheets have approximately I - V curve similar to behavior pure sheet with low sensing of current corresponds to bias and reverse voltages

تاثير امتزاز الغاز على الخصائص الالكترونية والتركيبية للجرافين المطعم == Effect of the Gas Adsorption on the Electronic and Structural Properties of Doped Graphene

Author name: صلاح عبد المهدي خضير
Supervisor name: حمد رحمن جبر
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University of Babylon - College Of Education For Pure Sciences - Physics Department
Language: English
University location: Babylon
First pages:
Abstract: تم حساب حساسية الجرافين النقي (PG) والجرافين المطعم بالنتروجين (N - doped graphene) والجرافين المطعم بالالمنيوم (Al - doped graphene) لسلسلة من جزيئات الغازات الصغيرة وهي CO وCO2 وNH3 وNO وNO2 وSO2 باستعمال برنامج كاوسين 09 الذي يطبق نظرية الكثافة العملية (DFT) بدالة Perdew - Burke - Ernzerhof (PBE) ومجموعة الاساس 6 - 31G. وقد تم استقصاء تاثير التطعيم بواسطة تغيير تركيز ذرات التطعيم بنسبة 2.4 % (بمقدار ذرة واحدة من النتروجين او الالمنيوم في 42 ذرة مضيفة). اظهرت النتائج ان امتزاز CO وCO2 وNH3 وNO وNO2 وSO2 على سطح الجرافين النقي والجرافين المطعم بالنتروجين يكون امتزاز فيزيائي ضعيف وبطاقة امتزاز (Ead) تتراوح بين eV (0.115 - الى 0.640)، باستثناء امتزاز الغازات NO2 وSO2 على الجرافين النقي التي يكون امتزازها كيميائي قوي، في هذه الحالة، الجرافين النقي يكون محفز او منشط، وهذا يقترح امكانية استعمال الجرافين النقي كمحفز خالي من المعدن. كذلك، يكون امتزاز NO2 وSO2 على الجرافين المطعم بالالمنيوم امتزاز فيزيائي ضعيف وبطاقة امتزاز تتراوح بين eV (0.298 الى 0.611)، وبعبارة اخرى يمكن ان يستعمل الجرافين المطعم بالالمنيوم كمتحسس جيد لغازات NO2 وSO2. على اية حال، يكون امتزاز الغازات CO وCO2 وNH3 وNO على الجرافين المطعم بالالمنيوم امتزاز كيميائي قوي وبطاقة امتزاز اكبر من eV1، ونتيجة لهذا التفاعل القوي فان الجرافين المطعم بالالمنيوم يكون محفز او منشط، وهذا يقترح امكانية هذا الجرافين كمحفز. علاوة على ذلك، تكون فجوة الطاقة (Eg) مفتوحة وبطرق مختلفة للجرافين النقي والجرافين المطعم بالنتروجين والجرافين المطعم بالالمنيوم عند امتزاز الغازات CO وCO2 وNH3 وNO وNO2 وSO2. كذلك، فان الجرافين المطعم بالنتروجين الممتز بجزيئة غاز SO2 له القدرة على منح الكترون، لانه يحتاج الى طاقة صغيرة لازالة الكترون ليصبح ايون موجب. تظهر الدراسة امكانية تطبيق الجرافين النقي كمتحسس جيد لغازات CO وCO2 وNH3 وNO والجرافين المطعم بالنتروجين كمتحسس جيد لغازات CO وCO2 وNH3 وNO وNO2 وSO2. توضح نتائجنا ان الخصائص الالكترونية للجرافين يمكن ان تعدل (تطور) بتطعيمها بالنتروجين والالمنيوم والامتزاز بالغازات لتستعمل لتصميم متحسسات كيميائية، وبالتالي يمكن ان يستخدم الجرافين لبناء متحسسات لاكتشاف جزيئات مخصصة. | The sensitivity of pristine graphene (PG), nitrogen - doped graphene (N - doped graphene) and aluminum - doped graphene (Al - doped graphene) toward a series of small gas molecules CO, CO2, NH3, NO, NO2 and SO2 by using Gaussian 09 program which applies the density functional theory (DFT) with Perdew - Burke - Ernzerhof (PBE) functional and 6 - 31G basis set. The effect of doping was investigated by varying the concentration of doping atoms 2.4% (one atom of nitrogen or aluminum in 42 host atoms). The results show that the adsorptions of CO, CO2, NH3, NO, NO2 and SO2 on PG and N - doped graphene are weak physisorption with an adsorption energy (Ead) ranging from ( - 0.115 to 0.640) eV, except the adsorption of NO2 and SO2 on PG are a strong chemisorption, in this case, the PG could catalyse or activate, suggesting the possibility of PG as a metal - free catalyst. Furthermore, the adsorptions of NO2 and SO2 on Al - doped graphene are weak physisorption with a Ead ranging from (0.298 to 0.611) eV, otherwise Al - doped graphene could be a good sensor for NO2 and SO2. However, the adsorptions of CO, CO2, NH3 and NO on Al - doped graphene are a strong chemisorption with Ead larger than 1 eV, due to the strong interaction, Al - doped graphene could catalyse or activate, suggesting the possibility of Al - doped graphene as a catalyst. Moreover, the energy gap (Eg) of PG, N - doped graphene and Al - doped graphene is opened upon adsorption of CO, CO2, NH3, NO, NO2 and SO2 in various ways. Also, the N - doped graphene with SO2 gas molecule adsorption has the ability to donating an electron, it needs a small energy to remove an electron to become a cation. The study demonstrates the feasibility of PG to be a good sensor for CO, CO2, NH3 and NO and N - doped graphene could be a good sensor for CO, CO2, NH3, NO, NO2 and SO2. The results reveal the electronic properties of graphene which modified by nitrogen and aluminum doping and molecules adsorption, that could be used to design chemical sensors, and graphene could be used to build sensors for the detection of particular molecules

نقل الالكترون خلال النقطة الكمية : التاثيرات الكهروحرارية وتاثيرات التبادل في نهجي كوندو ولاكوندو == Electron Transport Through A Quantum Dot: Thermoelectric Effects And Correlation Effects In Kondo And Non - Kondo Regimes

Author name: موسى كاظم شامر
Supervisor name: jenan majeed Al - mukh | shakier lbraheem easa
General topic: Physics
Specific topic: Electronics Physics
Degree: Doctorate
University: University Of Basrah - College Of Education For Pure Sciences
Language: English
University location: Basrah
First pages:

تاثير المنطقة البينية على اداء الكاشف الضوئي نوع حاجز شوتكي == EFFECT OF INTERFACIAL LAYER ON PERFERMANCE OF SCHOTTKY BARRIER PHOTODETECTOR

Author name: عايد نجم صالح الجبوري
Supervisor name: وكاع فرمان محمد
General topic: Physics
Specific topic: Electronics Physics
Degree: Doctorate
University: University of Al Mosul - College Of Science - Physics Department
Language: Arabic
University location: Mosul
First pages:

Synthesis And Properties Of Some New PPVD derivatives Applications In Pleds

Author name: باسل علي عبدول
General topic: Physics
Specific topic: Electronics Physics
Degree: Master
University: University Of Basrah - College Of Science
University location: Basrah
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