论文标题
氦纳米圆环中共振的原子间库仑衰变的时间分辨研究
Time-resolved study of resonant interatomic Coulombic decay in helium nanodroplets
论文作者
论文摘要
当弱结合的复合物通过强烈的电磁辐射倍增时，可以通过一种谐振的原子间库仑衰减（ICD）在相邻原子之间交换能量。预计由于多种激发而引起的这种衰减机制相对较慢，通常持续数十个picseconds。在这里，我们使用高分辨率，可调的，极端的无紫外电子激光器直接测量激发氦液滴中的ICD时间尺度。在广泛的液滴尺寸和激光强度的范围内，我们发现衰减的速度非常快，衰减时间的速度速度高达400个飞秒，并且仅表现出对激发态密度的弱依赖性。利用时间依赖性密度功能理论和量子量子化学计算的结合，我们阐明了这种超快衰变过程的机制，其中一个液滴中的一对激发的氦原子对彼此强烈吸引并形成了综合的空白气泡，从而大大加速了ICD。
When weakly-bound complexes are multiply excited by intense electromagnetic radiation, energy can be exchanged between neighboring atoms through a type of resonant interatomic Coulombic decay (ICD). This decay mechanism due to multiple excitations has been predicted to be relatively slow, typically lasting tens to hundreds of picoseconds. Here, we directly measure the ICD timescale in resonantly excited helium droplets using a high resolution, tunable, extreme ultraviolet free electron laser. Over an extensive range of droplet sizes and laser intensities, we discover the decay to be surprisingly fast, with decay times as fast as 400 femtoseconds, and to only present a weak dependence on the density of the excited states. Using a combination of time dependent density functional theory and ab initio quantum chemistry calculations, we elucidate the mechanisms of this ultrafast decay process where pairs of excited helium atoms in one droplet strongly attract each other and form merging void bubbles which drastically accelerates ICD.
