Case Studies: Low Energy Ion Scattering (LEIS) Spectroscopy

Low-energy ion scattering (LEIS) spectroscopy is the most surface-sensitive elemental analytical technique currently available with a depth resolution of one atomic layer (~0.3 nm). When combined with sputtering of the surface, it can also provide depth resolution profiles of the different elements present in a solid material. The LEIS measurement, however, requires ultrahigh vacuum (UHV) conditions in order to avoid altering the kinetic energy of the scattered ions by gas-gas collisions. Consequently, it is not possible to perform in situ and operando spectroscopy studies (Brongersma et al., Surf Sci Rep 62:63–109, 2007; Cushman et al., Anal Methods 8:3419–3439, 2016). The catalytic materials, however, can be exposed to reactive environments to condition or activate the catalyst before LEIS analysis. Several examples of LEIS surface analysis of catalytic materials employing high-sensitivity LEIS spectroscopy (ION-TOF Qtac¹⁰⁰) will be highlighted below.