Using a passively stable attosecond beamline for relative photoemission time delays at high XUV photon energies.

Arohi Jain,Hans Jakob Wörner,Anatoli Kheifets,Thomas Gaumnitz

doi:10.1364/oe.26.028604

Abstract

We present and demonstrate an experimental scheme that enables overlap-free reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) measurements at high extreme-ultraviolet (XUV) photon energies. A compact passively-stabilized attosecond beamline employing a multilayer (ML) mirror allows us to obtain XUV pulses consisting of only two odd high-harmonic orders from an attosecond pulse train (APT). We compare our new technique to existing schemes that are used to perform RABBITT measurements and discuss how our scheme resolves the limitations imposed by spectral complexity of the harmonic comb at high photon energies. We further demonstrate first applications of our scheme for rare gases and gas mixtures, and show that this scheme can be extended to gas-molecule mixtures.

Highlights

Attosecond spectroscopy has given insight into the fundamental properties of atoms and molecules [1,2,3,4,5]
A compact passively-stabilized attosecond beamline employing a multilayer (ML) mirror allows us to obtain XUV pulses consisting of only two odd high-harmonic orders from an attosecond pulse train (APT)
We compare our new technique to existing schemes that are used to perform RABBITT measurements and discuss how our scheme resolves the limitations imposed by spectral complexity of the harmonic comb at high photon energies

Summary

Introduction

Attosecond spectroscopy has given insight into the fundamental properties of atoms and molecules [1,2,3,4,5]. The RABBITT technique involves quantum path interference [24, 25] using an attosecond pulse train consisting of odd harmonics used as pump to ionize the atoms/molecules and the fundamental laser field as a probe. The presence of the IR field at frequency ωL results in degenerate quantum paths from consecutive high-harmonic (H) orders spaced by 2ωL and in sidebands (SBs) in the photoelectron spectrum. This results in (N + (N − 1)) × M peaks in the photoelectron spectrum. Spectral overlap of photoemission lines from different orbitals due to many harmonic orders is a shortcoming of this method that has limited RABBITT measurements to low photon energies

Methods

Discussion

Conclusion