Department of Physics, Lund Institute of Technology, P. O. Box 118, SE-221 00 Lund, Sweden.
Phys Rev Lett. 2010 Jul 30;105(5):053001. doi: 10.1103/PhysRevLett.105.053001. Epub 2010 Jul 27.
We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as a reference to measure a bound WP. We demonstrate our method by exciting helium atoms using an attosecond pulse (AP) with a bandwidth centered near the ionization threshold, thus creating both a bound and a free WP simultaneously. After a variable delay, the bound WP is ionized by a few-cycle infrared laser precisely synchronized to the original AP. By measuring the delay-dependent photoelectron spectrum we obtain an interferogram that contains both quantum beats as well as multipath interference. Analysis of the interferogram allows us to determine the bound WP components with a spectral resolution much better than the inverse of the AP duration.
我们提出了一种干涉式泵浦-探测技术，用于对阿秒电子波包（WP）进行特性分析，该技术使用自由 WP 作为参考来测量束缚 WP。我们通过使用带宽中心位于电离阈值附近的阿秒脉冲（AP）来激发氦原子，从而同时创建束缚 WP 和自由 WP。在经过一个可变延迟后，束缚 WP 被精确地与原始 AP 同步的几个周期的红外激光电离。通过测量延迟相关的光电子能谱，我们得到了一个干涉图，其中包含量子拍频和多路径干涉。对干涉图的分析使我们能够以比 AP 持续时间的倒数好得多的光谱分辨率确定束缚 WP 分量。
