Influence of shape resonances on the angular dependence of molecular photoionization delays

Abstract

Characterizing time delays in molecular photoionization as a function of the ejected electron emission direction relative to the orientation of the molecule and the light polarization axis provides unprecedented insights into the attosecond dynamics induced by extreme ultraviolet or X-ray one-photon absorption, including the role of electronic correlation and continuum resonant states. Here, we report completely resolved experimental and computational angular dependence of single-photon ionization delays in NO molecules across a shape resonance, relying on synchrotron radiation and time-independent ab initio calculations. The angle-dependent time delay variations of few hundreds of attoseconds, resulting from the interference of the resonant and non-resonant contributions to the dynamics of the ejected electron, are well described using a multichannel Fano model where the time delay of the resonant component is angle-independent. Comparing these results with the same resonance computed in e-NO+ scattering highlights the connection of photoionization delays with Wigner scattering time delays.

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.…”

An Investigation of the Resonant and Non-Resonant Angular Time Delay of e-C60 Elastic Scattering

“…The idea of angular time delay was published in 1963 by Froissart, Goldberger, and Watson [52] in the framework of S-matrix theory. In a similar approach, angular time delay in photoionisation also was defined [53]. Many recent experimental studies on atomic systems confirmed the angle-dependent nature of time delay in photoionisation [54,55].…”

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 ].…”