摘要
電子顯微鏡已經成為包括材料、化學、生物等各領域不可或缺的一項重要研究工具， 但隨著各領域需求的增加，原本電子顯微鏡做了更多的改良，4D電子顯微鏡就此產生， 4D電子顯微鏡不只擁有原本電子顯微鏡的高空間解析度的特性，我們藉著只包含少數電 子的波包，避開了電子間彼此干擾的space charge effect與Boerch effect，空間解析度也被 提高至更高等級，也就是說4D電子顯微鏡可以同時提高空間與時間的解析度，以及加入 了超快雷射，使原本的熱陰極電子顯微鏡加入了雷射的光激發效果，讓電子束被拉出，超 快雷射的輸出頻率亦是控制時間解析度的一項因素。 超快電子顯微鏡又稱四維度電子顯微鏡，由於跟傳統電子顯微鏡相較之下，提高了時 間解析度，我們可以觀察到更短暫時間內的變化，且預期將它廣泛的應用於材料學上細部 短暫動態變化的觀察，或化學反應中間過程的變化觀察，甚至對未來在醫學上的研究都是一大 利多。 在本論文中，我們首先設計出想要的機構，包括電子槍、透鏡部分、電子偏極板、奈 米等級以上的超快開關(photo-switch)、及接收電子訊號部分。燈絲被加熱與超快雷射的共 同作用之下，電子束被激發出來，經過了聚焦鏡的聚焦，再經由被photo-switch所控制的 偏轉器的偏轉，使電子束最後打在MCP上訊號被放大，我們預期在加入超快雷射前後會看 到電流值的大小變化，以證明超快雷射實際上有幫助電子束出現。
並列摘要
Electron microscope has become a pivotal instrument in materials, chemical, and biological field. But now, we use the single-electron packets to develop 4D ultrafast electron microscope, that the 4D-EM not only held the function of conventional EM, but also provides the structural of dyn- amic image and combined with spatial and temporal resolution . Because single-electron packets have no space- charge effect,and Boerch effect images patterns can observe with atomic- scale spat- ial resolution, and temporal resoluyion that is determined by the ultrafast laser pulses duration can achieve pico- or femtosecond scale. We also call ultrafast electron microscope as 4D electron microscope，because it improve more temporal resolution than conventional electron microscope，and we can observe the transient chan- ge。We hope that we will apply in materials science、chemical reaction or even in research of me- dical science。 In the research we design the electron gun chamber, deflection plate, sub-nanosecond electron switch and combined with MCP. Electrons are exciting from probe by ultrafast laser and focus on the specimen to produce electron signal. The electron signal deflects by adding electron field that is controlled by electron-optic switch in few picosecond and produce dispersion to separate the signal. The final signal is amplified when goes through MCP (multi channel plate) , and detected by phos- phor screen. We expect the current will increase by adding ultrafast laser. It will verify that ultrafast laser change the current of electron beam.
參考文獻
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