Mercadier L, Benediktovitch A, Weninger C, Blessenohl M A, Bernitt S, Bekker H, Dobrodey S, Sanchez-Gonzalez A, Erk B, Bomme C, Boll R, Yin Z, Majety V P, Steinbrügge R, Khalal M A, Penent F, Palaudoux J, Lablanquie P, Rudenko A, Rolles D, Crespo López-Urrutia J R, Rohringer N
Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.
European XFEL, 22869 Schenefeld, Germany.
Phys Rev Lett. 2019 Jul 12;123(2):023201. doi: 10.1103/PhysRevLett.123.023201.
We present a comprehensive experimental and theoretical study on superfluorescence in the extreme ultraviolet wavelength regime. Focusing a free-electron laser pulse in a cell filled with Xe gas, the medium is quasi-instantaneously population inverted by 4d-shell ionization on the giant resonance followed by Auger decay. On the timescale of ∼10 ps to ∼100 ps (depending on parameters) a macroscopic polarization builds up in the medium, resulting in superfluorescent emission of several Xe lines in the forward direction. As the number of emitters in the system is increased by either raising the pressure or the pump-pulse energy, the emission yield grows exponentially over four orders of magnitude and reaches saturation. With increasing yield, we observe line broadening, a manifestation of superfluorescence in the spectral domain. Our novel theoretical approach, based on a full quantum treatment of the atomic system and the irradiated field, shows quantitative agreement with the experiment and supports our interpretation.
我们对极紫外波长范围内的超荧光进行了全面的实验和理论研究。将自由电子激光脉冲聚焦在充满氙气的腔室中，通过巨共振上的4d壳层电离以及随后的俄歇衰变，介质被准瞬时地实现粒子数反转。在大约10皮秒到100皮秒的时间尺度上（取决于参数），介质中会形成宏观极化，从而导致几条氙线在向前方向上产生超荧光发射。随着通过提高压力或泵浦脉冲能量来增加系统中的发射体数量，发射产率呈指数增长，跨越四个数量级并达到饱和。随着产率的增加，我们观察到谱线展宽，这是超荧光在光谱域中的一种表现。我们基于对原子系统和辐照场进行全量子处理的新颖理论方法，与实验结果在定量上吻合，并支持我们的解释。
