  In this Master Thesis, we use a technique to shift and stack the X-Ray
spectra of 1138 galaxy clusters from the eRASS-1 survey, totalling 430649
counts. In comparison with previous stacking techniques, the method presented
here introduces proper normalization of the shifted redistribution matrix file
(RMF), which allows to recover the physical temperature and metallicity of the
stacked spectra. Using this technique, we can obtain constraints in the stacked
spectra for the individual abundances of O, Ne, Mg, Si, Ar, Ca, and Fe.
Additionally, we study the possible detection of the previously reported 3.5keV
unidentified line emission; however, the residuals barely exceed $\pm 2 \sigma$
in the [3-4]keV range. On the other hand, although residuals in the
[3.4-3.55]keV band are compatible with charge exchange emission from SXVI (bare
sulphur ions), charge exchange emission from OVII at 0.56keV should also be
present, since it is 200 orders of magnitude higher than charge emission from
SXVI in the [3.4-3.55]keV band; however, it is unfortunately not detected.
