Measuring the photoelectron emission delay in the molecular frame

Abstract

How long does it take to emit an electron from an atom? This question has intrigued scientists for decades. As such emission times are in the attosecond regime, the advent of attosecond metrology using ultrashort and intense lasers has re-triggered strong interest on the topic from an experimental standpoint. Here, we present an approach to measure such emission delays, which does not require attosecond light pulses, and works without the presence of superimposed infrared laser fields. We instead extract the emission delay from the interference pattern generated as the emitted photoelectron is diffracted by the parent ion’s potential. Targeting core electrons in CO, we measured a 2d map of photoelectron emission delays in the molecular frame over a wide range of electron energies. The emission times depend drastically on the photoelectrons’ emission directions in the molecular frame and exhibit characteristic changes along the shape resonance of the molecule.

Trends in angle-resolved molecular photoelectron spectroscopy

“…109,334 In this context, K-shell ionization of CO recently led to the extraction of MF angle resolved photoionization time-delays. 335…”

Attosecond dynamics of multi-channel single photon ionization

“…Advances towards the characterization of the complex-valued ionization channel amplitudes 6 – 8 have been achieved by determining the electron spin 9 , 10 , or alternatively measuring (or preparing) the residual ion alignment and orientation with sophisticated experimental protocols including coincidence techniques 11 and/or the combination of light fields with several polarization components 12 – 14 . As a result of these decades of efforts, two recent studies using molecular frame photoelectron angular distribution imaging have succeeded to measure single-photon 15 , 16 angle-resolved phases in molecules up to an isotropic but energy-dependent phase.…”

Discrimination of Excited States of Acetylacetone through Theoretical Molecular-Frame Photoelectron Angular Distributions

“…In the case of core ionization, MFPADs also represent a suitable tool to examine the nature of the shape resonance [ 17 , 18 , 19 ], and to probe the presence of doubly excited states, imprinted in their profiles [ 20 , 21 , 22 ]. Moreover, they can be used to extract the photoelectron emission delay [ 23 ], avoiding the use of attosecond light pulses [ 24 ].…”