本文關鍵詞：磁性酞菁錳分子在半金屬表面的STM研究　出處：《西南大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 酞菁錳 轉動態(tài) 吸附構型 背散射 掃描隧道顯微鏡

【摘要】：在納米技術領域中,分子可作為自下而上構建功能性納米結構的重要基石�；谙冗M的化學合成技術,人們利用分子的新奇性質和分子納米結構來筑造許多可控且靈活的分子器件。因此,功能性分子無疑會成為制備具有多功能的納米設備的基本材料之一。金屬表面分子吸附體系正好可用于研究分子在表面的結構和性質,為進一步構筑高功能分子納米結構提供先決條件。同時,對分子在金屬表面的吸附體系的研究也有助于人們認識表面物理、化學、生物現(xiàn)象。目前,人們利用具有原子分辨的表征和操縱能力的掃描隧道顯微鏡(STM),并結合掃描隧道譜學(STS)及其他分析手段,在研究單分子吸附體系中已經(jīng)取得了豐碩的成果。當然,STM也在金屬表面分子吸附體系研究中展現(xiàn)出獨特的優(yōu)勢。在本論文中,我們利用超高真空低溫掃描隧道顯微鏡研究了吸附在半金屬Bi(111)表面的磁性酞菁錳分子體系。第一章介紹了納米科技的前沿知識和國際納米技術發(fā)展水平。各種新奇的低維材料的出現(xiàn)及其特殊性質為納米科技的發(fā)展不斷注入新的活力。其次,介紹了低維材料的制備及其表征方法,低維材料制備可以在原子級或分子級可控,而且可以原位生長和表征樣品,使得測量結果更加準確,進而獲得樣品的本征特性。其中我們側重闡述了薄膜的成核與生長過程機制理論描述。最后,結合研究課題的內(nèi)容介紹了目前掃描隧道顯微鏡在研究金屬表面分子體系中取得的成果,如表面分子運動實時監(jiān)控、表面分子操縱等等。第二章主要介紹了本實驗室使用的超高真空低溫強磁場STM系統(tǒng)USM1500。主要介紹了實驗中所涉及的超高真空技術、分子束外延技術、低溫強磁場技術以及STM的基本結構與工作原理。詳細地介紹了先進的掃描隧道譜技術,該技術能夠表征樣品表面局域的電子態(tài)密度,并且能夠測量電子態(tài)密度分別以空間和能量為變量的分布。利用掃描隧道顯微鏡微分電導譜和成像技術能夠直接研究分子結構、分子軌道及分子襯底之間的相互作用。第三章介紹了我們利用低溫STM研究了半金屬Bi(111)表面上單個酞菁錳分子的吸附行為和轉動特性。通過高分辨STM圖發(fā)現(xiàn),在液氮溫度(78 K)下單個酞菁錳分子呈六角形形狀。利用STM操縱技術實現(xiàn)了對單個酞菁錳分子的制動,并通過對單分子的高低起伏和吸附構型分析,確定分子在Bi(111)表面做非連續(xù)的中心轉動。這種單分子轉動是三種相對穩(wěn)定的吸附構型交替變化的結果。結合STM的I-t譜技術,進一步驗證了單個MnPc分子的三種分子吸附構型的存在。利用洛倫茲線形擬合對實驗統(tǒng)計值擬合分析,得到單個轉動的MnPc分子在Bi(111)表面的三種不同的吸附構型出現(xiàn)的概率及其相對能量,從而確定出最穩(wěn)定的吸附構型。在第四章中,我們主要利用LT-STM的微分電導成像技術對包含有磁性酞菁錳分子的區(qū)域進行成像,觀察表面局域電子態(tài)密度的分布。通過快速傅里葉變化(FFT)技術,我們發(fā)現(xiàn)在4.6 K和78 K下單分子磁體對Bi(111)表面電子態(tài)密度的散射模式中存在背散射,并且在4.6 K下分子對表面態(tài)的散射模式依賴于分子在Bi(111)表面上的吸附方向,從而證明MnPc分子的自旋磁矩可以打破Bi(111)表面的時間反演對稱性的保護。
[Abstract]:In the field of nanotechnology, molecular can be used as an important cornerstone of bottom-up construction of functional nanostructures. The chemical synthesis technology based on advanced people use novel properties and molecular structure of nano molecular molecular devices to build many controllable and flexible. Therefore, functional molecules will undoubtedly become one of the preparation of multifunctional nano device the basic molecular material. The metal surface adsorption system just can be used to study the molecular structure and properties of the surface, providing a precondition for further fabrication of high functional nanostructures. At the same time, the study of adsorption on the metal surface of the molecular system also helps people understand the surface physical, chemical and biological phenomena. At present, scanning tunneling people with atomic resolution microscopy characterization and manipulation ability (STM), and scanning tunneling spectroscopy (STS) and other analytical methods in the study of single molecules Have achieved fruitful results in adsorption system. Of course, STM also in the study of molecular metal surface adsorption system shows unique advantages. In this paper, we use the ultra high vacuum low temperature scanning tunneling microscope was studied in semi metal Bi (111) surface magnetic molecular KCeO2MnPcX phthalein system. The first chapter introduces nanometer science and technology knowledge and international nanotechnology development. A variety of novel low dimensional materials have special properties and for the development of nano science and technology continue to inject new vitality. Secondly, introduces the method of preparation and characterization of low dimensional materials, low dimensional materials can be prepared at the atomic or molecular level controlled. But also the growth and characterization of in situ samples, the measurement result is more accurate, the intrinsic properties of obtained samples. We focuses on the thin film theory of nucleation and growth process mechanism described. Finally, node Research topics are introduced in scanning tunneling microscopy study of metal surface molecular system achievements, such as surface molecular motion real-time monitoring, surface molecular manipulation etc. the second chapter mainly introduces the laboratory using ultra high vacuum low temperature and high magnetic field STM system USM1500. is introduced to the ultra high vacuum technology experiment in molecular beam epitaxy, the basic structure and working principle of low temperature and high magnetic field technology and STM. This paper introduces the advanced scanning tunneling spectrum technology, the technology can characterize the local surface electron density, and can measure the density of electronic states respectively in space and energy for the distribution of variable differential by scanning tunneling microscopy. The conductance spectrum and imaging technology can directly study the molecular structure, the interaction between the molecular orbitals and the substrate. The third chapter introduces the Low temperature STM of semi metal Bi (111) adsorption behavior on the surface of a single molecule Manganese Phthalocyanine and rotational characteristics. Through the map found high resolution STM, at the temperature of liquid nitrogen (78 K) under a hexagonal shape. Manganese Phthalocyanine molecular manipulation technology to achieve the braking of a single molecule of Manganese Phthalocyanine by STM, and through the single the ups and downs of molecular adsorption and configuration analysis, determine the molecules on Bi (111) non continuous rotation center surface. This is the three single molecular rotation adsorption configuration relatively stable alternating results. Combined with the STM I-t spectrum technology, further validation of the three kinds of molecular adsorption configuration of single MnPc molecules in value exist. Fitting analysis of experimental statistics using Lorenz linear fitting, a single rotation of the MnPc molecules on Bi (111) the probability of occurrence of three different adsorption configurations on the surface and the relative energy, so as to determine the most stable adsorption configurations. In the fourth chapter, we mainly use the differential conductance imaging LT-STM for imaging magnetic Manganese Phthalocyanine molecular region to contain, to investigate the distribution of the local surface density of electronic states. By fast Fourier transform (FFT) technique, we found that at 4.6 K and 78 K single molecular magnets of Bi (111) backscattering scattering the surface of the electronic density of States, and the molecular scattering mode at 4.6 K on the surface states depend on molecules on Bi (111) adsorption on the surface so as to prove the direction, the spin magnetic moment of MnPc molecule can break the Bi (111) surface protection time reversal symmetry.

【學位授予單位】：西南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.1;O561

【共引文獻】

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本文編號：1432662