title: Attosecond electron spectroscopy using a novel interferometric pump-probe technique.
abstract: 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.
authors.affiliation: Department of Physics, Lund Institute of Technology, P. O. Box 118, SE-221 00 Lund, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Mauritsson
authors.forename: T
authors.initials: T
authors.lastname: Remetter
authors.forename: M
authors.initials: M
authors.lastname: Swoboda
authors.forename: K
authors.initials: K
authors.lastname: Klünder
authors.forename: A
authors.initials: A
authors.lastname: L'Huillier
authors.forename: K J
authors.initials: KJ
authors.lastname: Schafer
authors.forename: O
authors.initials: O
authors.lastname: Ghafur
authors.forename: F
authors.initials: F
authors.lastname: Kelkensberg
authors.forename: W
authors.initials: W
authors.lastname: Siu
authors.forename: P
authors.initials: P
authors.lastname: Johnsson
authors.forename: M J J
authors.initials: MJ
authors.lastname: Vrakking
authors.forename: I
authors.initials: I
authors.lastname: Znakovskaya
authors.forename: T
authors.initials: T
authors.lastname: Uphues
authors.forename: S
authors.initials: S
authors.lastname: Zherebtsov
authors.forename: M F
authors.initials: MF
authors.lastname: Kling
authors.forename: F
authors.initials: F
authors.lastname: Lépine
authors.forename: E
authors.initials: E
authors.lastname: Benedetti
authors.forename: F
authors.initials: F
authors.lastname: Ferrari
authors.forename: G
authors.initials: G
authors.lastname: Sansone
authors.forename: M
authors.initials: M
authors.lastname: Nisoli