Table : Few PSC materials and X-ray absorption edges in the soft X-ray regime of the elements involved XAS of these materials were simulated with the help of Henke database in the soft X-ray regime, from ~100 eV to 2800 eV, and are presented in figures . For the simulation, thicknesses are randomly chosen, and the densities used have been those that are available either in the literature or have been roughly estimated. The purpose of these spectra is to show the presence or absence of various edges in the soft X-ray regime. Figure shows the XAS of various A, B and X site complexes/atoms. As can be observed, many absorption edges of these materials lie in the selected soft X-ray energy region. This implies that if sufficient concentration of these complexes/atoms is present in the sample, detection could be possible in STXM. shows the XAS from 250 to 750 eV. As mentioned earlier, it is worth noting that the C K-edge and N K-edge could be especially interesting as these belong to the inner shell transitions and could have NEXAFS features (fine structure) that could be very sensitive to chemical functionalities. NEXAFS has been widely used for a variety of materials and has been recently applied to PSC materials to disentangle degradation mechanisms . Experimental spectra of various PSC materials were also obtained. Figure In order to demonstrate the effectiveness of XAS and to disentangle the detection of one element over another we have previously presented several materials that were carefully chosen (KI, PbCl2). This demonstration also included degradation products PbO and PbI2.