几种低维纳米结构在金与银的（110）面上的结构与物性

发布时间：2018-05-13 20:53

本文选题：超高真空-变温-扫描隧道显微镜系统 + 链状分子　；参考：《中国科学院大学(中国科学院物理研究所)》2017年博士论文

【摘要】：本论文主要介绍合作搭建的超高真空(UHV)-变温(VT)-光学扫描隧道显微镜(OSTM)系统和利用该系统开展的相关研究工作,包括链状分子(4,4"-二氨基对三联苯(DAT)与并五苯)在Au(110)上的生长与结构研究和在Ag(110)上利用固态碳源生长准自由态石墨烯纳米岛等。此外,由于STM系统在化学分析和时间分辨方面上的能力较弱,超快激光技术与STM系统结合,能弥补STM系统该方面的能力缺失,为此设计并搭建了激光耦合STM系统的超快激光光路部分。1.合作搭建的超高真空-变温-扫描隧道显微镜系统包括了系统结构,泵路,气站,针尖与样品处理台,扫描头,连续流低温恒温器以及光学调整台等部分。在系统搭建完成后,对系统的各项功能进行了测试。在室温下利用该系统能够获得Au(111)表面清晰的原子图像,且该系统变温操作简单快速,在各个温度下都能有很好的成像能力。由于后续的实验工作都是在该系统上完成的,都获得了很好的实验数据。因而,该系统性能优秀,已达到预期的设计目标。2.通过改变样品退火温度实现调控单层4,4"-二氨基对三联苯(DAT)分子在Au(110)表面上的生长结构。单层DAT分子沉积在Au(110)表面后,样品低温(100℃)退火,会使得表面形成(1×5)重构结构,DAT分子会以肩并肩方式居中吸附在该沟道中,形成梯子型结构。样品退火200℃后,Au(110)表面形成(1×5)与(1×3)两种重构结构。对于(1×5)重构结构中的DAT分子,单端氨基会脱去两个氢原子并与Au原子形成N-Au键,以-2H-DAT形式吸附在该沟道中。而对于(1×3)结构中的DAT分子,所有分子以头接头方式吸附在该沟道中但仅部分DAT分子双端氨基全部脱氢以-4H-DAT结构存在。当样品退火350℃后,Au(110)表面仅存(1×3)重构结构,所有DAT分子双端脱氢,以-4H-DAT结构吸附在该重构结构中。相关的DFT理论计算证明(1×5)重构结构中的DAT分子脱氢与金成键势垒较(1×3)重构结构中的DAT分子脱氢势垒小,这也验证了实验结论。这样通过改变样品退火温度,可以调控DAT分子在Au(110)表面上的自组装结构。3.在Au(110)上通过调控并五苯分子覆盖度和退火温度,能够形成一维金属有机结构。并五苯分子从亚单层到单层的生长过程中,样品退火200℃会诱使Au(110)表面形成(1×3)与(1×6)的重构结构,并五苯分子分别以头接头方式与肩并肩方式排布在这两种结构中。由于并五苯分子与Au(110)表面间的相互作用,(1×6)重构结构中的并五苯分子中心会表现出小亮点。对单层并五苯样品退火250℃后,并五苯分子仅存在于(1×6)的沟道中,且通过并五苯分子中心的-CH与金原子形成的配位键作用,生成了一维金属有机链状结构。该结构的形成不借助于有机分子的特殊官能团,且能保留并五苯分子的本征特性。最后在单层并五苯样品上继续生长双层并五苯结构,退火200℃后,发现顶层分子仅排布在底层的(1×3)结构上,且成拱形结构。4.在Ag(110)表面上利用固态碳源可以生长出准自由态的石墨烯纳米岛。实验中发现,通过改变碳原子的沉积速率和衬底温度,可以调控石墨烯纳米岛的质量与形貌。在较小的沉积速率和较高的衬底温度时,生成的石墨烯纳米岛质量最好。并且通过拉曼光谱,STS一阶谱以及STM针尖操纵证明了该石墨烯为准自由态石墨烯。由于石墨烯与Ag(110)表面的晶格失配,在Ag(110)表面形成了多种线条状的摩尔超结构,通过构建的理论结构模型,证明该结构确实源于石墨烯与Ag(110)表面的晶格失配。5.由于STM系统在时间分辨和化学分析方面上的能力较弱而激光技术在这方面具有很多优势,因而将超快激光技术与STM系统结合,有希望全面提升STM系统的研究能力,在超高时空分辨能力,针尖增强拉曼光谱以及激光诱导化学反应或形变等体系研究上有很好的前景。因此,设计并搭建激光耦合STM系统的超快激光光路部分,还对激光入射到隧道结的过程和工作模式进行了分析。这对于后续的相关研究,起到重要作用。
[Abstract]:This paper mainly introduces the cooperative UHV - VT - optical scanning tunneling microscope (OSTM) system and the related research work carried out by using this system, including the growth and structure of the chain molecules (4,4 "- two amino pairs of three biphenyl (DAT) and five benzene) on Au (110) and the quasi free growth of solid carbon source on Ag (110). In addition, due to the weak ability of STM system in chemical analysis and time resolution, ultra fast laser technology and STM system can make up for the lack of ability in this aspect of the STM system. To this end, the ultra high vacuum and temperature change scanning of the ultra fast laser light path part of the laser coupled STM system is designed and built by.1.. The tunnel microscope system includes the system structure, the pump, the gas station, the needle tip and the sample processing table, the scanning head, the continuous current low temperature thermostat and the optical adjustment table. After the system is completed, the functions of the system are tested. The system can obtain the clear atomic image on the Au (111) surface at room temperature, and the system can be obtained at room temperature. The temperature change operation is simple and fast and can have good imaging ability at all temperatures. Since the subsequent experiment is done on the system, good experimental data have been obtained. Therefore, the system has excellent performance and has reached the expected design goal.2. to control single layer 4,4 "- two amino pairs by changing the annealing temperature of the sample. The growth structure of benzene (DAT) molecule on the surface of Au (110). After the monolayer DAT molecule is deposited on the Au (110) surface, the sample is annealed at low temperature (100 degrees C), which will make the surface form (1 * 5) restructure. The DAT molecule will be adsorbed in the channel and form a ladder type structure. After the sample annealing 200 c, the surface of Au (110) is formed (1 x 5) and two species (1 * 3). For the DAT molecule in the (1 * 5) reconstruction structure, the single terminal amino group will remove two hydrogen atoms and form a N-Au bond with the Au atom and adsorb in the channel in the form of -2H-DAT. For the DAT molecule in the (1 * 3) structure, all the molecules are adsorbed in the channel by the head joint mode, but only some of the DAT molecules are dehydrogenated to -4H-DAT The structure exists. When the sample is annealed at 350 C, the surface of Au (110) is only (1 * 3) reconfigurable. All DAT molecules dehydrogenate at two ends and adsorb in the structure with -4H-DAT structure. The related DFT theoretical calculation shows that the DAT molecular dehydrogenation and gold bond potential barrier (1 * 3) in the reconstructed structure are smaller than the DAT dehydrogenation barrier in the reconstruction structure (1 * 3), which is also verified. By changing the annealing temperature, the self assembled structure of DAT molecules on the Au (110) surface can be regulated by the regulation of the Au (110) and the five benzene molecular coverage and annealing temperature, which can form a one-dimensional metal organic structure. And the annealing of the five benzene molecules from the submonolayer to the monolayer can induce the A to induce the A. U (110) surface formation (1 x 3) and (1 x 6) reconstruction structure, and five benzene molecules are arranged in the head joint way and shoulder to shoulder in the two structures. Because of the interaction between the five benzene molecules and the surface of the (110) (110), the molecular Center of the five benzene in the (1 * 6) reconstruction structure will show a small bright spot. After annealing of the monolayer and five benzene sample, And five benzene molecules exist only in the (1 x 6) channel, and by the coordination bond between the -CH and the gold atoms of the five benzene molecular center, a one-dimensional metal organic chain structure is formed. The structure is formed without the aid of the special functional groups of organic molecules, and can retain the intrinsic properties of the five benzenes. Finally, the structure is followed by a single layer and five benzene sample. The structure of double decker and five benzene is continued. After annealing at 200 c, it is found that the top layer molecules are arranged only on the (1 * 3) structure, and the arched structure.4. can grow the quasi free graphene nanometer island by the solid carbon source on the surface of Ag (110). It is found that the graphene can be regulated by changing the deposition rate of carbon atoms and the substrate temperature. The quality and morphology of nanoscale island. At smaller deposition rate and higher substrate temperature, the produced graphene nanoscale is of the best quality. Through Raman spectra, the first order spectrum of STS and the manipulation of STM tip prove that the graphene is quasi free graphene. Because of the lattice mismatch between the graphene and the Ag (110) surface, the surface of the Ag (110) is formed much more. The mole superstructure of a linear strip has proved that the structure does originate from the lattice mismatch between graphene and Ag (110) surface by constructing a theoretical structural model. The laser technology has a lot of advantages in this respect because of the weak ability of the STM system in time resolution and chemical analysis. Therefore, the ultra fast laser technology is combined with the STM system. We hope to improve the research capacity of STM system, and have good prospects in the study of ultra high time resolution, needle tip enhanced Raman spectroscopy and laser induced chemical reaction or deformation. Therefore, the ultra fast laser path part of laser coupled STM system is designed and built, and the process and working mode of laser incident to the tunnel junction are also introduced. Analysis is carried out, which plays an important role in subsequent related research.

【学位授予单位】：中国科学院大学(中国科学院物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1;TH742

【相似文献】