Niikura Hiromichi, Légaré F, Hasbani R, Bandrauk A D, Ivanov Misha Yu, Villeneuve D M, Corkum P B
National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A OR6, Canada.
Nature. 2002 Jun 27;417(6892):917-22. doi: 10.1038/nature00787.
Experience shows that the ability to make measurements in any new time regime opens new areas of science. Currently, experimental probes for the attosecond time regime (10(-18) 10(-15) s) are being established. The leading approach is the generation of attosecond optical pulses by ionizing atoms with intense laser pulses. This nonlinear process leads to the production of high harmonics during collisions between electrons and the ionized atoms. The underlying mechanism implies control of energetic electrons with attosecond precision. We propose that the electrons themselves can be exploited for ultrafast measurements. We use a 'molecular clock', based on a vibrational wave packet in H(2)(+) to show that distinct bunches of electrons appear during electron ion collisions with high current densities, and durations of about 1 femtosecond (10(-15) s). Furthermore, we use the molecular clock to study the dynamics of non-sequential double ionization.
经验表明，在任何新的时间尺度下进行测量的能力都会开辟新的科学领域。目前，阿秒时间尺度（10^(-18)至10^(-15)秒）的实验探测手段正在建立。主要方法是用强激光脉冲电离原子来产生阿秒光脉冲。这种非线性过程会在电子与电离原子碰撞时产生高次谐波。其潜在机制意味着能以阿秒精度控制高能电子。我们提出电子本身可用于超快测量。我们使用基于H₂⁺中振动波包的“分子钟”来表明，在具有高电流密度且持续时间约为1飞秒（10^(-15)秒）的电子 - 离子碰撞过程中会出现不同的电子束团。此外，我们使用分子钟来研究非顺序双电离的动力学。
