Angle-resolved study of resonant Auger decay and fluorescence emission processes after core excitations of the terminal and central nitrogen atoms in ${\mathrm{N}}_2\mathrm{O}$

Angular distributions of the ${\mathrm{N}}_2$${\mathrm{O}}^{+}\left(X\right)$ and ${\mathrm{N}}_2$${\mathrm{O}}^{+}\left(A\right)$ photoelectrons were measured as functions of the exciting-photon energy with small bandwidth in the vicinity of the resonant ${\mathrm{N}}_t(1s\to {\pi }^{*})$, ${\mathrm{N}}_t(1s\to {\sigma }^{*})$, and ${\mathrm{N}}_c(1s\to {\pi }^{*})$ core excitations of ${\mathrm{N}}_2\mathrm{O}$. For selected exciting-photon energies in this range, angular distribution parameters of the ${\mathrm{N}}_2$${\mathrm{O}}^{+}(A\to X)$ fluorescence were also determined. These data are interpreted by ab initio calculations. Long-range exciting-photon energy dependencies of the photoelectron angular distribution parameters ${\beta }_X^e\left(\omega \right)$ and ${\beta }_A^e\left(\omega \right)$, recorded vibrationally unresolved, are attributed to an electronic state interference between the direct and the different resonant amplitudes for the population of the final ionic states. In addition to that, strong influence of lifetime vibrational interference is identified in the observed dispersion of the vibrationally resolved fluorescence angular distribution parameter $\beta 2_A^X\left(\omega \right)$ across the electronic resonances.

Figure 1

The total ion and fluorescence yields measured in the present work in the vicinity of the ${\pi }_t^{*}$, ${\sigma }_t^{*}$, and ${\pi }_c^{*}$ resonances of ${\mathrm{N}}_2\mathrm{O}$ (the energy positions are indicated by vertical bars) together with the presently computed broadband excitation spectrum obtained via the three-dimensional nuclear dynamics calculations. All spectra are normalized at the maximum. For further details, see Secs. 3 and 4.

Figure 2

Relative cross section for the population of the ${\mathrm{N}}_2$${\mathrm{O}}^{+}\left(X\right)$ final ionic state (top panel) and photoelectron angular distribution parameter (bottom panel) measured in the present work in the vibrationally unresolved regime and computed in different approximations (see legends and text for details). Experimental and theoretical cross sections are equalized at their maxima, whereas no normalization for asymmetry parameter is required. The typical experimental error $\left(1\sigma \right)$ is shown in the bottom panel by the vertical bar.

Figure 3

Parameters measured and computed for the ${\mathrm{N}}_2$${\mathrm{O}}^{+}\left(A\right)$ final ionic state (see notations in Fig. 2).

Figure 4

Angular distribution parameter for the $A,{\chi }^{\prime }\left(000\right)\to X,{\chi }^{\prime \prime }$ fluorescence bands progression of the ${\mathrm{N}}_2$${\mathrm{O}}^{+}$ ion measured in the present work in the vibrationally resolved regime and computed in different approximations (see legend and also text for details). The typical experimental error $\left(1\sigma \right)$ is shown by the vertical bar.