title: Conclusive evidence of an attosecond pulse train observed with the mode-resolved autocorrelation technique.
abstract: We report on the direct observation of an attosecond pulse train with a mode-resolved autocorrelation technique. The chirp among the three harmonic fields is specified by analyzing two-photon above-threshold ionization spectra of electrons, resulting in a pulse duration that should be shorter than 450 as, which is, to our knowledge, the first determination of the chirp in the attosecond pulse train with an autocorrelation technique. These results will open the way to full characterization of an attosecond pulse train with its envelope.
authors.affiliation: RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. nabekawa@riken.jp
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nabekawa
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Shimizu
authors.forename: Tomoya
authors.initials: T
authors.lastname: Okino
authors.forename: Kentaro
authors.initials: K
authors.lastname: Furusawa
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Kaoru
authors.initials: K
authors.lastname: Yamanouchi
authors.forename: Katsumi
authors.initials: K
authors.lastname: Midorikawa