Photoelectron angular distribution studies of the outer valence states of N₂

Abstract

We present angle resolved photoelectron data for the ionization of all N 2 outer valence shells namely the 3σ g , 1π u and 2σ u states in the photon energy region from 19 to 50 eV with a photon energy step width down to 20 meV. Signatures due to the autoionization of doubly excited Rydberg states and the corresponding vibrational progression are observed in the dipole electron angular distribution parameter β. They are compared with recent calculations. We also find evidence for theoretically predicted sharp resonance effects due to channel coupling in the electron angular distribution of 1 π −1 u. Shape resonance and channel coupling effects are discussed for all outer valence orbitals with respect to recent theoretical findings.

Resonant scattering and diffraction beamline P09 at PETRA III

“…The QPBM, the slit system, the diamond screen and the diamond window are mounted on a granite table equipped with a horizontal and vertical translation to align them in the beam. An in-line electron time-of-flight (eToF) polarization monitor using photoelectrons from a gas target will be positioned on the same table in the near future (Ilchen et al, 2009). This device will allow online monitoring of the incident polarization during polarization manipulation of the incident beam using the phase-retarder set-up.…”

Precise Access to the Molecular-Frame Complex Recombination Dipole through High-Harmonic Spectroscopy

“…PACS numbers: 32.70.-n, 42.65.Ky, 42.65.Re Molecular-frame photoionization and recombination [1][2][3][4] contains a rich abundance of information about orbital structure and dynamics that is washed-out in traditional [5] extreme-ultraviolet (XUV) spectroscopy of randomly-oriented molecules. Knowledge of molecular orientation in most valence-shell photoionization experiments requires using laser-induced impulsive pre-alignment techniques [6] when the ion does not dissociate, thus necessitating short-pulsed XUV sources for spectroscopy like high-order harmonic generation (HHG) [7], femtosecond sliced synchrotrons [8], or freeelectron lasers [9].…”

Direct Imaging of Transient Fano Resonances inN2Using Time-, Energy-, and Angular-Resolved Photoelectron Spectroscopy

“…In principle, two processes are possible at the observed photoelectron kinetic energy, namely, XUV þ IR ionization in the B channel and XUV-IR ionization (n ¼ −1 sideband) in the X channel. However, since one-photon photoemission in both the X and B channels is known to peak along the laser polarization [25] and both XUV and IR pulses are linearly polarized in the same direction, we expect that the nonresonant two-photon process should also lead to signals peaking along the laser polarization. This contradicts our observations and forces us to exclude nonresonant processes as the cause of the observed transient.…”