掃描式穿隧顯微術的三核與十一核鎳金屬串錯合分子電性結構之研究

本論文研究Au(111)單晶表面的[Ni3(dpa)4(NCS)2]與[Ni11(bnatpya)4(NCS)2]4+兩不同長度的一維金屬串分子的排列結構與電性表現。利用超高真空掃描穿隧顯微鏡(UHV-STM)進行樣品製備與表面分析。實驗方法為先準備Au(111)單晶表面；選擇易揮發的二氯甲烷作為溶劑配製金屬串分子溶液，再使用微量吸管滴至表面上而得[Ni3(dpa)4(NCS)2]/Au(111)及[Ni11(bnatpya)4(NCS)2]4+/Au(111)樣品。第一部分，STM影像顯示[Ni3(dpa)4(NCS)2]在Au(111)表面傾向吸附在台階邊緣(step edge)上，且可從高度剖面圖獲知單一金屬串分子的高度；利用掃描穿隧能譜(STS)技術取得dI/dV能譜，可獲得[Ni3(dpa)4(NCS)2]在Au(111)表面上的能態密度資訊，發現有兩個特徵峰，分別為−0.65 eV以及−0.10 eV。為了從影像上更易判斷分子的特徵，改以較長的[Ni11(bnatpya)4(NCS)2]4+分子滴至表面，STM影像顯示[Ni11(bnatpya)4(NCS)2]4+在表面上無序地排列，而且受到咖啡環效應的影響，分子會以一至多個重複的單體分布在表面上。利用STS分別在團簇與單一分子上得到dI/dV能譜，結果顯示團簇的負偏壓位置出現寬廣的疊加波峰。第二部分，將腔體溫度降至78 K的實驗環境，以減少分子與探針受到熱擾動的影響，從STM影像觀察到單一金屬串分子的電子雲呈現左旋以及右旋的構型，其金屬軸向與螺旋狀電子雲間約50o的夾角；此外，還觀察到少數分子的電子雲非左、右旋構型，而是與金屬軸向呈約90o的夾角。

關鍵字

掃描穿隧顯微術；掃描穿隧能譜；能階密度； Au(111) ； [Ni3(dpa)4(NCS)2] ； [Ni11(bnatpya)4(NCS)2]4+

並列摘要

This study discuss the arrangement and electricity of two one-dimensional metal string molecules [Ni3(dpa)4(NCS)2] and [Ni11(bnatpya)4(NCS)2]4+ which are different lengths on the Au(111) surface. Sample preparation and surface analysis were obtained by ultrahigh vacuum scanning tunneling microscope (UHV-STM). The samples were prepared by dissolving the metal string molecular with the CH2Cl2 solvent, then drop on the surface of Au(111) and obtaining the [Ni3(dpa)4(NCS)2]/Au(111) and [Ni11(bnatpya)4(NCS)2]4+/Au(111). In the first part, the STM image shows that [Ni3(dpa)4(NCS)2] is adsorbed on the step edge of Au(111) surface, and the height of single metal string molecule could obtained from the height profile. The dI/dV spectra of [Ni3(dpa)4(NCS)2] on Au(111) revealed two characteristic peaks, −0.65 eV and −0.10 eV by the scanning tunneling spectroscopy (STS) .To make sure the molecular characteristics from the image, using the longer molecules of [Ni11(bnatpya)4(NCS)2]4+ to drop on the surface, and the STM image shows the molecules are disorderly and distributed on the surface with one or more repeating monomers by the coffee ring effect. The dI/dV spectrum on the cluster and the single molecule, respectively, the results show that the cluster has a broad peak at the negative bias. In the second part, the chamber is cooled to 78 K to reduce the influence of the thermal disturbance of the molecule and the tip. From the STM images, the electron cloud of single metal string molecule exhibits a left-handed and right-handed configuration with an angle of about 50o between the metal axis and the helical electron cloud. In addition, it is observed that the electron cloud of some molecules reveal non-left and right hand but rather about 90o with the metal axis.

並列關鍵字

Scanning tunneling microscope ； Scanning tunneling spectroscopy ； density of state ； Au(111)、[Ni3(dpa)4(NCS)2] ； [Ni11(bnatpya)4(NCS)2]4+

參考文獻

(1) Lörtscher, E. Wiring molecules into circuits. Nat. Nanotechnol. 2013, 8, 381-384.

(2) Wilson, L. International technology roadmap for semiconductors (ITRS). Semiconductor Industry Association 2013.

(3) Nitzan, A.; Ratner, M. A. Electron transport in molecular wire junctions. Science 2003, 300, 1384-1389.

(4) He, J.; Chen, F.; Liddell, P. A.; Andréasson, J.; Straight, S. D.; Gust, D.; Moore, T. A.; Moore, A. L.; Li, J.; Sankey, O. F. Switching of a photochromic molecule on gold electrodes: single-molecule measurements. Nanotechnology 2005, 16, 695.

(5) Venkataraman, L.; Klare, J. E.; Nuckolls, C.; Hybertsen, M. S.; Steigerwald, M. L. Dependence of single-molecule junction conductance on molecular conformation. Nature 2006, 442, 904-907.

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掃描式穿隧顯微術的三核與十一核鎳金屬串錯合分子電性結構之研究

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