Single sub-fs soft-X-ray pulses: generation and measurement with the atomic transient recorder

Abstract

The change from a zero transition to the maximum amplitude of the electric field of visible light lasts shorter than one femtosecond (1 fs = 10−15 s). By precisely controlling the hyperfast electric field oscillations in a short laser pulse we developed a measuring apparatus—the atomic transient recorder—like an ultrafast stopwatch. This apparatus is capable of measuring the duration of atomic processes with an accuracy of less than 100 as (1 as = 10−18 s), which is the typical duration of electronic processes (transients) deep inside atoms. A 250 as X-ray pulse initiates the atomic process to be measured and the attosecond stopwatch at the same time. For the first time it is now possible with this new measuring method to observe ultrafast processes in the electron shell of atoms.