過渡金屬碳化物與氮化物是便宜而且極具發展潛力的貴金屬催化劑替代品，而在過渡金屬表面上成長碳化層更是能同時具備碳化物與金屬的優點。鉬（110）面上的（4×4）結構碳化層在早前已被證實具有類似貴金屬的催化特性，並且已經應用在許多表面反應的研究中，但是關於鉬（110）表面碳化層的實際表面結構確仍然不清楚。在本文中，我們使用乙烯（C2H4）在鉬（110）面上依不同的碳化條件製作了兩種不同結構的碳化層：（4×4）結構和長方格結構，同時使用低能量電子繞射（LEED）和掃描穿隧顯微鏡（STM）來研究樣品表面上的結構。
乾淨的鉬（110）表面可以通過一般的樣品清潔程序得到。而後我們將碳化實驗分成了三個主軸：在800K曝乙烯、在室溫曝乙烯、在室溫曝離子化的乙烯。在這三大項中又依不同的曝氣後退火條件可再細分成：曝氣後不退火、於600K退火、於800K退火、於900K退火、於1000K以上退火，碳化程序完成後等樣品溫度降到室溫即進行LEED與STM實驗。在本文中同時也對鉬（110）面在真空中所受到的污染作了一些探討，並且作了一個表面氧化實驗來對照。
經實驗我們發現在同樣的退火條件與曝氣溫度下，乙烯曝量較高的案例其碳化表面為（4×4）結構，由STM影像來看（4×4）結構碳原子的覆蓋率可能是1/16；乙烯曝量較低者為具有2個domain的長方格結構，這個結構的碳原子覆蓋率可能為1/30，同時發現在長方格結構在曝量低或退火、曝氣溫度高的情況下，從STM影像中會看到樣品表面有高覆蓋率的無結構區域，這些無結構的區域經推測可能是不含碳的（1×1）鉬（110）面或是一些含碳量低的相的集合。從這些實驗結果中我們可以知道乙烯曝氣後隨著退火的時間進行，碳原子會逐漸往樣品內部滲透。

Transition metal carbides and nitrides are the potential and cheap substitutes for the noble metals in heterogeneous catalysis. In addition, the carbide overlayers grown on the surfaces of transition metal have the advantages of carbides and metal. The carbide overlayer of (4x4) structure on Mo(110) surface has been confirmed to possess the noble metal-like catalytic properties and been studied in many investigations of surface reaction. However, the (4x4) structure in real space is unknown so far. In this study, molybdenum carbide overlayers were fabricated by carburizing the Mo(110) surface with ethylene (C2H4). Under various carburizing conditions, two carbide structures were produced: the (4x4) and “rectangle” structures. The structures of carbide overlayers were investigated by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM).
The carburization was carried out on clean Mo(110) surface which could be obtained by standard cleaning recipe of metal surfaces. Carburizing conditions include two main factors: the exposure of C2H4 and the post-annealing. Three recipes of C2H4 exposure were carried out in this study: exposing on 800 K and RT surface and exposure of ionized C2H4 on RT surface. Each exposure recipe was followed by annealing at various temperatures, including 600, 800, 900, and 1100 K. The contamination of Mo(110) surface in UHV was also investigated and compared with the oxidized Mo(110) surface.
The (4x4) structure was formed at higher exposures, and from the STM images the carbon coverage on this surface was likely to be 1/16 ML. At lower exposures, the “rectangle” structure was formed which had two domains and a possible carbon coverage of 1/30 ML. The “rectangle” structure coexisted with non-identified area which probably was the (1x1) structure of Mo(110) surface or structure of much lower carbon coverage. The inward diffusion of carbon atoms during annealing was confirmed from the results of this study.

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