隨著超高功率超短脈衝雷射系統的發展，高強度雷射脈衝與物質交互作用的研究，在近年來受到極大的重視。其中除了常用的氣體或固體靶材之外，以高速氣體噴流中由凡得瓦力結合而成的原子團簇為靶材，更是有許多非常重要的發展。由於原子團簇本身內部的密度接近固體，而整體的平均密度則是與氣體相同，因此，原子團簇可以非常有效率地吸收雷射光，游離形成奈米尺度的高溫高密度電漿球[1]，而放射出高能的電子[2]、離子[3]、X 光[4]。最近更證實其可以做為內層電子躍遷硬X 光雷射的增益界質[5]。
為了更進一步瞭解甚至控制雷射與原子團簇的交互作用，我們以高強度紅外線雷射脈衝游離氬原子團簇來形成氬離子奈米電漿球，並驅動其膨脹與振盪，然後我們以氪氣X 光雷射所輸出的 32.8-nm 超快 X 光脈衝來探測此氬離子奈米電漿球對於 X 光的吸收，以釐清其隨時間的演化，未來希望這些資訊能夠協助我們發展更高效率更短波長的原子團簇內層電子躍遷硬X 光雷射。

Following continued advances in the table-top high-power laser system, the interaction of high-intensity laser pulses with matter has been studied intensively over
the past decade. Fruitful results have been obtained by using low-density gas or high-density solid as targets. Beside these two targets, many developments have also
achieved by using cluster target which is normally produced inside a high-pressure gas jet and combined by van der Waal’s force. A gaseous cluster target produces a
unique combination of gas and solid phase components. Their solid-like local density and gas-like average density cause individual nanometer clusters efficiently to absorb laser energy, forming highly-charged hot nanoplasmas [1]; to eject KeV electrons [2] and MeV ions [3], and to emit soft x-ray laser [4]. It is also proved that cluster target can be the gain medium of the hard x-ray laser emitted from the hollow atoms [5].
In order to understand or even control the laser-cluster interactions, we ionize argon cluster by infrared laser pulse to form a nanoplasma and then induce it to expand and
oscillate. After that, we use soft x-ray laser pulse to probe the argon nanoplasma and observe the absorption of x-ray for it.
We want to clarify the time resolution of expansions and oscillations of nanoplasma ionized by infrared laser pulse, and hope to get some useful information from our
research to develop the efficient and smaller-wavelength hard x-ray laser emitted from hollow atoms in the future.

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