在現今的電子顯微鏡中，穿隧式電子顯微鏡（TEM）具有亞埃級的空間分辨率，我們可以利用其優良的空間分辨率得到許多有價值的信息，以理解從物理系統到生物系統的廣泛問題。然而，在許多化學反應過程，分子反應過程反應時間為飛秒級（10-15秒），但傳統的TEM並沒有這種水準的時間分辨率。這項研究的目的是設計和構建電子顯微鏡的脈衝電子源，為電子顯微鏡增加飛秒分析能力。
對於雷射激發脈衝電子光源，如果用於成像，則有兩個障礙，即空間和時間相干性，需要克服。差的空間和時間相干性主要因為雷射激發電子的尺寸來自大約幾微米的區域且部分為熱游離電子，這阻礙了對原子的空間分辨率。
因此，我們使用光輔助場發射電子的原理，利用場發射電子具有低發散角及高能量相干性，從而提高空間相干性。同時，利用飛秒脈衝激光激發產生飛秒脈衝電子束的電子，從而獲得高空間分辨率且具有飛秒級別的高時間分辨率的脈衝電子束。
為達成上述目的，我們利用CO2雷射光纖熔拉機製備光纖奈米針尖 (針尖曲率半徑<100nm)，並利用電子束熱蒸鍍系統及脈衝雷射沉積系統將光纖針尖前端鍍上金屬 (Cr、Au、W)，再將飛秒脈衝雷射導入光纖，使脈衝雷射由背向激發電子至高能階，再配合適當電場使高能階電子穿隧場發射出電子，如此一來即可結合脈衝雷射特性製作出一飛秒脈衝電子光源。
我們亦架設出一穩定的飛秒雷射系統 (飛秒雷射震盪器、雷射一級放大器、雷射脈衝延展及壓縮器、雷射二倍頻)且設計出可以將雷射導入場發射電子槍超高真空腔體以利測試電子束性質，綜上述的準備以利我們進行實驗測試。

Transmission Electron Microscopes (TEM) have sub-angstrom spatial resolution and have provided valuable information to understand a broad range of problems from physical to biological systems. However, molecular processes occur at fast rates, femtoseconds (10-15 seconds), but conventional TEM does not have this level of time resolution. The purpose of this work was to design and build a pulsed electron source for electron microscopes to add femtosecond analysis capability to electron microscopes.
In this experiment, we established a high-coherence pulse electron source based on the principle of photo-assit field emission. Because of field emission electrons have excellent properties (low divergence angle and high energy coherent), we can improve spatial coherence in electron microscopy. At the same time, the femtosecond pulsed laser is used to excite the electrons and generate the femtosecond pulsed electron beam. Thereby, we can obtain high spatial resolution and high time resolution pulsed electron source.
In order to achieve the above objectives, we use a CO2 laser fiber thermal puller to prepare a fiber nano-tip (the tip radius of curvature <100nm), and use the electron beam thermal evaporation system and the pulse laser deposition system to coat the the fiber tip with metal (Cr,Au,W). Then, we couple the femtosecond pulse laser into the fiber so that we can accomplish the purpose of this experiment. And we have also set up a stable femtosecond laser system and designed an ultrahigh vacuum electron gun chamber.

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