Attosecond Time Delays in Photodetachment of Nitrate Anion

Measuring attosecond time delays provides information about the wave-function phase in photoionization

processes, thus providing insight into the electronic dynamics and structure of atomic and molecular systems.

In contrast to the photoionization of neutral species that have been extensively studied in the last decade,

photodetachment of negative ions has received much less attention, especially experimentally due to challenges

in preparing the anions. Since the outgoing photoelectron interacts

with a neutral species after the detachment, the absence of the long-range Coulomb potential allows easier observation

of correlation and polarization effects.

To stimulate experimental efforts in photodetachment time delay measurements, we conducted ab initio theoretical studies

 of valence and core photodetachment of nitrate anion (NO₃^-). In both cases, the nitrate anion exhibits

several shape resonances at low photoelectron energies below 20 eV with time delays up to 600 attoseconds.

In this contribution, we will present our simulations of the

 RABITT (Reconstruction of Attosecond Beating by Two-photon Transitions) and Streaking experiments

 in molecular and laboratory frames using the R-matrix method. We will discuss the effect of the additional IR 

 field on the direct measurement of the one-photon (Wigner) delay that is directly related to the detachment dynamics

 induced by the high-frequency field.