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Generation of Broadband Tunable Coherent X-rays by Using Optical Field Induced Ionization

利用光场诱导电离产生宽带可调谐相干 X 射线

基本信息

批准号：
09450033
负责人：
SASAKI Wataru
金额：
$ 5.82万
依托单位：
Miyazaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

We have demonstrated vacuum ultraviolet emissions from pulsed rare gas jet excited by a high intensity ultrashort pulse laser. Various emission characteristics are investigated thoroughly. Ultrashort pulse Lasers are also used to control the dissociation process of alkali halide molecules in a femtosecond time scale. These knowledge should be used to develop a practical coherent x-ray source in the laboratory scale.As a result of the interaction of Ar and high intensity laser field, we have observed emissions from Ar_2^* at 126 nm for the first time together with some signals of high order harmonics. The focused laser intensity dependence of the Ar excimer intensity agrees well with that predicted by a tunnel ionization theory so called ADK theory. We, therefore, found out that the production of Ar excimers was initiated by high intensity laser produced electrons, which may become a substitution to those produced by an electron beam device.Experimental data show no difference in terms of the Ar excimer emission when linearly polarized and circularly polarized laser beams interacted with Ar. Considering about the energy transport of electrons in a high intensity laser produced plasma theoretically, we have found out a rapid conductive cooling of a plasma plays an important role for the excimer pioduction.The control of a molecule by using a high intensity laser has been demonstrated in the femtosecond time region as well. Alkali halide molecules have been excited and deexcited by using two different wavelength (ultraviolet and visible) lasers, which leads to the coherent control of the molecule with the minimum thermal effect This type of coherent molecular control means that the molecule can become a good optical amplifier even in a very short wavelength range, and can become a new coherent x-ray source.

我们用高强度超短脉冲激光激发稀有气体脉冲射流，实现了真空紫外辐射。各种发射特性进行了深入研究。超短脉冲激光也被用于在飞秒时间尺度内控制碱金属卤化物分子的解离过程。利用Ar与强激光场的相互作用，我们首次观测到了Ar_2 ^~* 的126 nm辐射和一些高次谐波信号。聚焦激光强度的Ar准分子强度的依赖性同意很好的隧道电离理论，即所谓的ADK理论预测。结果表明，Ar准分子的产生是由高强度激光产生的电子引发的，可以替代电子束装置产生的电子，线偏振和圆偏振激光与Ar相互作用时，Ar准分子的发射没有差别。从理论上考虑了强激光等离子体中电子的能量输运，发现等离子体的快速传导冷却对激基准分子的产生起着重要的作用，并在飞秒时间范围内论证了强激光对分子的控制。碱金属卤化物分子已经通过使用两种不同波长（紫外和可见）的激光进行激发和去激发，这导致了具有最小热效应的分子的相干控制这种类型的相干分子控制意味着分子即使在很短的波长范围内也可以成为良好的光放大器，并且可以成为新的相干X射线源。