Hartman et al. employed XPEEM to investigate the valence band maximum of defects formed in MAPbI(3-X)ClX on TiO2. Spatially-resolved surface chemical composition was identified by using XPS mode in XPEEM. High-energy resolution fluorescence detection (HERFD) XAS (X-ray absorption spectroscopy) was used by Drisdell et al. to investigate MAPb(BrxI1-x) with various halide ratios. Sterling et al. investigated the sensitivity of Nitrogen K-edge XAS to halide substitution and thermal fluctuations in Methylammonium lead halide perovskites single crystals. In this theoretical and experimental study, they observed a blue shift of the spectra by 0.31 eV in the case of MAPbBr3 compared to MAPbI3. Dunfield et al. used angles resolved photoemission electron spectroscopy (ARPES) in TEY mode (total electron yield) to prove that the Fermi level shift was not related to the near surface MA-dipole orientation. Wheeler et al. used XAS data to further verify the cation-exchange mechanism upon treatment of the CsPbI3 QD Quantum Dot) films with the FAI (formamidinium Iodide) solution.