近年來由於環境的污染與破壞，因此為了改善環境，光觸媒已經成為研究的重點之ㄧ。當光觸媒在照射到紫外光時，由於電子電洞對的產生，其表面能夠產生高活性的分子，可以將有機物質分解成水與二氧化碳等分子。根據文獻，大部分的研究都是在研究如何改善環境，少部分有提到應用在改質上，但還未應用到奈米尺度下。為了研究在奈米尺度下此一反應的行為，我們以掃描探針微影技術(Scanning Probe Lithography, SPL)來進行相關研究。利用濺鍍有二氧化鈦薄膜的原子力顯微鏡探針與自組裝分子膜表面的接觸，研究其在紫外光照射下的表面改質的效果及其應用。 本研究中利用光觸媒的特性將奈米尺度的自組裝有機分子膜表面官能基分解而達到改質的目的，主要量測方式是利用側向原子力顯微鏡(簡稱 LFM)。實驗結果顯示二氧化鈦探針在照射紫外光後可使自組裝分子十八基三氯矽烷產生官能基改變與分解作用。在濺鍍二氧化鈦薄膜時會影響到原子力顯微鏡探針的雷射反射值而影響靈敏度，所以在濺鍍時必須要探針懸臂懸空防止濺鍍到探針懸臂背部。實驗中已經成功的利用原子力顯微鏡將光觸媒應用於自組裝單分子膜表面改質，並且可以在奈米尺度下改質局部區域。而且二氧化鈦光觸媒的薄膜厚度、紫外光的強度影響著光觸媒的強弱。如果選擇二氧化鈦薄膜較薄的探針進行表面改質時，尺度可達50 nm左右，而且可以進行特定符號或是文字的改質。而且根據光觸媒的的強弱再做分析，發現其衰退的半衰期約為1小時，而且二氧化鈦探針會因為實驗的進行而效果逐漸衰弱，發現是因為針尖表面被雜質覆蓋，但經由電漿將雜質清除後又可以再度進行實驗。而如果要消除二氧化鈦探針光觸媒的效果，則可以浸泡在去離子水中將活性分子消除。 In recent years, in order to improve the environment, the photocatalysis has been studied intensitvely. Under illumination of UV light, the surface of TiO2 produces active oxygen, which can decompose organic matters into water and carbon dioxide, etc. According to references, most of research is to study how to improve the environment. Little portion of the study is to focus at local photocatalytic decomposition of self-assembled monolayers. But there are not modifying surfaces with resolution in the nanometer range. In this work, we demonstrate a novel local photocatalytic decomposition based on scanning probe lithography with TiO2-coated probes. We find that when the activated probe contacts the surface of octadecyltrichlorosilane (OTS) self-assembled monolyaer (SAM), the active oxygenic species could diffuse to the substrate, resulting in local modification of the SAM surface.The results of this local photocatalytic decomposition process are studied by lateral force microscopy (LFM). We are successful to demonstrate a novel SPM lithography method based on the local photocatalytic decomposition near the TiO2-coated probe. The thickness of coated TiO2 and the power intensity of the UV light influence the efficience of the photocatalysis. With the thinner TiO2, the size of reacted area can reach about 50 nm. Patterns written by this method are demonstrated. We find that photocatalytic half life time of the illuminated probes is about an hour, so the photocatalysis will become weaker gradually during the experiments. The tip is contaminated by the chemical byproduct. It can be revived by a plasma cleaning.
