2008/12/04 by P. Eckle, Adrian N. Pfeiffer, Claudio Cirelli +5 · 8 citations
Physics and Astronomy · #Laser-Matter Interactions and Applications #Advanced Fiber Laser Technologies #Laser-Plasma Interactions and Diagnostics
paper · doi:10.1126/science.1163439
openalex publication_date 2008/12/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is well established that electrons can escape from atoms through tunneling under the influence of strong laser fields, but the timing of the process has been controversial and far too rapid to probe in detail. We used attosecond angular streaking to place an upper limit of 34 attoseconds and an intensity-averaged upper limit of 12 attoseconds on the tunneling delay time in strong field ionization of a helium atom. The ionization field derives from 5.5-femtosecond-long near-infrared laser pulses with peak intensities ranging from 2.3 x 10(14) to 3.5 x 10(14) watts per square centimeter (corresponding to a Keldysh parameter variation from 1.45 to 1.17, associated with the onset of efficient tunneling). The technique relies on establishing an absolute reference point in the laboratory frame by elliptical polarization of the laser pulse, from which field-induced momentum shifts of the emergent electron can be assigned to a temporal delay on the basis of the known oscillation of the field vector.