Experimental methods in chemical engineering:<scp>X</scp>‐ray absorption spectroscopy—<scp>XAS</scp>,<scp>XANES</scp>,<scp>EXAFS</scp>

Although X-ray absorption spectroscopy (XAS) was conceived in the early 20th century, it took 60 years after advent of synchrotrons for researchers to exploit its tremendous potential. Counterintuitively, are now developing bench type polychromatic sources that less brilliant measure catalyst stability and work with toxic substances. XAS measures spectra electrons X-rays eject from tightly bound core continuum. The spectrum 10 150 eV (kinetic energy photoelectrons) above chemical potential—binding electrons—identifies oxidation state band occupancy (X-ray near edge structure, XANES), while higher energies relate local atomic structure like coordination number distance, Debye-Waller factor, inner potential correction (extended fine EXAFS). Combining complementary spectroscopic techniques Raman, Fourier transform infrared (FTIR), photoelectron (XPS), electron paramagnetic resonance (EPR) elucidates nature bonds at surface better understand reaction mechanisms intermediates. Because continue be light source choice most researchers, articles Web Science indexes per year has grown 1000 1991 1700 2020. Material scientists physical chemists publish an order magnitude more than engineers. Based on a bibliometric analysis, research comprises five clusters centred around: electronic optical properties, hydrogenation catalysis, analytical FTIR, nanoparticles electrocatalysis, iron, metals, complexes.