Fe VII emission lines in the wavelength range 193-197 \AA

TL;DR

This paper identifies and measures Fe VII emission lines in the 193-197 Å range, providing new experimental energies and improving atomic data for solar EUV spectral analysis.

Contribution

It reports new laboratory measurements of Fe VII lines, identifies two previously unreported lines, and refines atomic data for solar spectral diagnostics.

Findings

Two new Fe VII emission lines identified.

New experimental energies for key levels provided.

Density diagnostics applied to solar spectra.

Abstract

The identifications of Fe VII emission lines in the wavelength range 193-197 {\AA} are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra from the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft, which has its peak sensitivity at these wavelengths. Ten lines are measured, arising from seven fine structure levels in the $3p^53d^3$ configuration. Two lines have not previously been reported and lead to new experimental energies for the $(a^2D)^3F_{2,3}$ levels. Updated experimental energies are obtained for the remaining levels. The new atomic model is used to compute theoretical values for the two density diagnostic ratios $\lambda$196.21/$\lambda$195.39 and $\lambda$196.21/$\lambda$196.06, and densities are derived from EIS spectra of coronal loop footpoints.