Observation of the angle-resolved resonant Auger emission from the $\left[1s2p\right]\left({}^{3,1}P\right)3p^2$ ${}^{1}P$ doubly excited $2p\text{−}2h$ states of $\mathrm{Ne}$

A high-resolution photoabsorption spectrum of $\mathrm{Ne}$ has been measured in the energy range of the $\left[1s2p\right]n\ell n^{\prime }{\ell }^{\prime }$ doubly excited states, where square brackets indicate hole states, by means of photoion yield spectroscopy. The observed features have been interpreted by adopting a simple Rydberg formula. Energies as well as quantum defects for the members of the $\left[1s2p\right]\left({}^{3,1}P\right)3pnp$ $\left(3⩽n⩽5\right)$ series have been determined. We report observations of angle-resolved spectra of the resonant Auger (RA) transitions to the ${\mathrm{Ne}}^{+}$ $\left[2p^3\right]3p^2$ states and to the ${\mathrm{Ne}}^{+}$ $\left[2s2p^2\right]3p^2$ states from the $\left[1s2p\right]\left({}^{3,1}P\right)3p^2$ doubly excited states. These double-spectator-type transitions are confirmed by a good general agreement between the measured and theoretical RA spectra, where theoretical spectra are calculated based on the Hartree-Fock approximation. The measured anisotropy parameters are compared with theoretical predictions calculated using a pure $LS$ coupling approach. We have made assignments for several levels with the aid of theoretical calculations.

Figure 1

Absorption spectrum in the region of the $\left[1s2p\right]n\ell n^{\prime }{\ell }^{\prime }$ doubly excited states with the unfolded Fano profile fit. Arrows indicate the photon energies at which the Auger electron spectra were measured. The energies of the $\left[1s2p\right]\left({}^{3,1}P\right)3pnp$ series are shown as a bar graph in the lower part of the figure.

Figure 2

Angle-integrated Auger electron spectra recorded in the region of the doubly excited states for seven different photon energies indicated by arrows in Fig. 1. The NA lines are marked with their final-state configurations.

Figure 3

Typical examples of the electron spectra of the RA as well as the NA transitions recorded at photon energies of (left) $902.37\mathrm{eV}$ and (right) $905.32\mathrm{eV}$ with horizontal (closed circles) and vertical (open circles) polarizations.

Figure 4

(a) Angle-integrated Auger electron spectrum measured at an incident photon energy of $902.37\mathrm{eV}$ and calculated Auger rates of the NA (closed bar), the $\left[2p^3\right]3p^2$ RA (shaded bar), and the $\left[2s2p^2\right]3p^2$ RA (open bar) transitions from the $\left[1s2p\right]\left({}^{3}P\right)3p^2$ $2p\text{−}2h$ state, respectively. (b) The same as (a) except for the $\left[1s2p\right]\left({}^{1}P\right)3p^2$ state measured at a photon energy of $905.32\mathrm{eV}$.