Abstract
Ultrafast processes are now accessible on the attosecond time scale due to the availability of ultrashort XUV laser pulses. Noble-gas and halogen atoms remain important targets due to their giant dipole resonance and Cooper minimum. Here, we calculate photoionization cross section, asymmetry parameter and Wigner time delay using the time-dependent local-density approximation (TDLDA), which includes the electron correlation effects. Our results are consistent with experimental data and other theoretical calculations. The asymmetry parameter provides an extra layer of access to the phase information of the photoionization processes. We find that halogen atoms bear a strong resemblance on cross section, asymmetry parameter and time delay to their noble-gas neighbors. Our predicted time delay should provide a guidance for future experiments on those atoms and related molecules.
Highlights
Photoionization processes are traditionally studied using high-resolution synchrotron radiations [1,2], which provides detailed information about the electronic structure of the target.A complete description of photoionization requires information on both the amplitude and phase of the dipole transition matrix elements, through the measurement of cross sections and asymmetry parameter.Thanks to the development of attosecond XUV-IR laser pump-probe technology [3,4,5], it is possible to observe and control ultrafast processes in matter on their natural time scale of attoseconds
The giant dipole resonance is a well-known feature in many atomic photoionization spectra, which is a resonance-like broad peak that occurs above single-photon ionization threshold
We present our calculations of partial photoionization cross sections, asymmetry parameters, phase shifts, and Wigner time delay for noble-gas and halogen atoms
Summary
Photoionization processes are traditionally studied using high-resolution synchrotron radiations [1,2], which provides detailed information about the electronic structure of the target. The giant dipole resonance is a well-known feature in many atomic photoionization spectra, which is a resonance-like broad peak that occurs above single-photon ionization threshold. It has been interpreted as originating from a potential barrier in a particular one-electron ionization channel [49,50] or as originating from a many-electron, collective oscillation of the atomic electrons [51,52]. We introduce the theoretical methods, present our results, reveal the resemblance between noble-gas and halogen atoms, and discuss the features of Wigner time delay near the giant dipole resonance and Cooper minimum.
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