Use of a laser as a femtosecond ruler to precisely measure an x-ray pulse

Abstract

The photoelectron spectra (PES) excited by narrow bandwidth femtosecond x rays in the presence of a femtosecond laser were investigated. Two transfer equations were found which can be used to precisely reconstruct the detailed x-ray profile from the measured PES. The reconstruction is a direct procedure without any previous pulse-shape assumption. The method has high time resolution and broad temporal measurement range which depend on the laser and x-ray parameters.