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arXiv · 2009.08669

The role of dipole-forbidden autoionizing resonances in non-resonant one-color two-photon single ionization of N$_2$

Kirk A. Larsen·Roger Y. Bello·Robert R. Lucchese·Thomas N. Rescigno·C. William McCurdy·Daniel S. Slaughter·Thorsten Weber
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Abstract

We present an experimental and theoretical energy- and angle-resolved study on the photoionization dynamics of non-resonant one-color two-photon single valence ionization of neutral N$_2$ molecules. Using 9.3 eV photons produced via high harmonic generation and a 3-D momentum imaging spectrometer, we detect the photoelectrons and ions produced from one-color two-photon ionization in coincidence. Photoionization of N$_2$ populates the X $^2\Sigma^+_g$, A $^2\Pi_u$, and B $^2\Sigma^+_u$ ionic states of N$_2^+$, where the photoelectron angular distributions associated with the X $^2\Sigma^+_g$ and A $^2\Pi_u$ states both vary with changes in photoelectron kinetic energy of only a few hundred meV. We attribute the rapid evolution in the photoelectron angular distributions to the excitation and decay of dipole-forbidden autoionizing resonances that belong to series of different symmetries, all of which are members of the Hopfield series, and compete with the direct two-photon single ionization.

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Kirk A. Larsen, Roger Y. Bello, Robert R. Lucchese, Thomas N. Rescigno, C. William McCurdy, Daniel S. Slaughter, Thorsten Weber. 2020-09-18. The role of dipole-forbidden autoionizing resonances in non-resonant one-color two-photon single ionization of N$_2$. https://doi.org/10.1103/physreva.102.063118

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