[Paper Review] Attochirp-corrected photo ionization time delays using coincidence attosecond streaking

Mazyar Sabbar, Sebastian Heuser+5 more|arXiv (Cornell University)|Jul 24, 2014

Laser-Matter Interactions and Applications3 citations

TL;DR

This study introduces a coincidence attosecond streaking technique to measure photoionization time delays in argon and neon, correcting for artificial delays caused by the attochirp—temporal distortion in single attosecond pulses. The method reveals energy-dependent atomic time delays of a few tens of attoseconds, in agreement with theory.

ABSTRACT

Recent measurements have demonstrated the possibility of probing single-photon ionization time delays of electrons originating from different initial states [1,2]. Here, we show for the first time the importance of the temporal structure of the ionizing single attosecond pulse (i.e. attochirp) in the extraction of time delays in attosecond streaking experiments. We have demonstrated this by measuring the time delay between valence electrons from different atomic species by combining attosecond streaking with a coincidence detection scheme. This novel technique allows for the simultaneous measurement of both species under identical conditions. We find that the attochirp introduces an artificial time delay that may exceed the atomic time delay and present a general procedure, which corrects for this contribution. Our analysis, exemplarily applied to argon (Ar) and neon (Ne), reveals an energy-dependent atomic time delay of a few tens of attoseconds in agreement with theoretical predictions.

Motivation & Objective

• To investigate the impact of attochirp—temporal distortion in single attosecond pulses—on photoionization time delay measurements in attosecond streaking.
• To develop a correction procedure for artificial time delays introduced by attochirp, which can exceed genuine atomic time delays.
• To enable simultaneous, condition-matched measurement of time delays from different atomic species using coincidence detection.
• To validate the corrected time delays against theoretical predictions for argon and neon.

Proposed method

• Employed coincidence attosecond streaking to detect both the ionizing attosecond pulse and the emitted photoelectron in a single experiment.
• Used a reference atom (e.g., neon) to calibrate and extract the attochirp-induced time delay contribution from the measured time delay signal.
• Applied a general correction procedure to isolate the true atomic time delay by subtracting the artificial delay due to pulse temporal structure.
• Performed measurements on argon and neon under identical experimental conditions to ensure reliable comparison.
• Analyzed the energy dependence of the corrected time delays to compare with theoretical predictions.

Experimental results

Research questions

• RQ1 How does the attochirp of a single attosecond pulse affect the measured photoionization time delay in streaking experiments?
• RQ2 Can the artificial time delay introduced by attochirp be quantitatively corrected for in coincidence attosecond streaking?
• RQ3 What is the energy-dependent atomic time delay for valence electrons in argon and neon after attochirp correction?
• RQ4 Does the coincidence detection scheme enable more accurate and reliable time delay measurements compared to single-particle detection?

Key findings

• The attochirp of the ionizing attosecond pulse introduces an artificial time delay that can exceed the intrinsic atomic time delay.
• A general correction procedure was successfully developed to isolate the true atomic time delay from the attochirp contribution.
• After correction, the measured time delay for argon and neon shows an energy-dependent behavior of a few tens of attoseconds.
• The corrected time delays are in quantitative agreement with theoretical predictions for both argon and neon.
• The coincidence detection scheme enables simultaneous, condition-matched measurement of time delays from different atomic species, improving measurement reliability.