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. © 2010 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Mauritsson, J., Remetter, T., Swoboda, M., Klünder, K., L'Huillier, A., Schafer, K., Ghafur, O., Kelkensberg, F., Siu, W., Johnsson, P., Vrakking, M., Znakovskaya, I., Uphues, T., Zherebtsov, S., Kling, M., Lépine, F., Benedetti, E., Ferrari, F., Sansone, G., & Nisoli, M. (2010). Attosecond electron spectroscopy using a novel interferometric pump-probe technique. Physical Review Letters, 105 (5) https://doi.org/10.1103/PhysRevLett.105.053001