In Situ Microscopy and Spectroscopy Applied to Surfaces at Work

The present review discusses the current state of the art microscopic and spectroscopic characterization techniques available to study surfaces and interfaces under working conditions. Microscopic techniques such as environmental transmission electron microscopy and in situ transmission electron microscopy are first discussed showing their applications in the field of nanomaterials and catalysis. Next sum frequency generation vibrational spectroscopy is discussed, giving probing examples of surface studies in gaseous conditions. Synchrotron based X-ray techniques are also examined with a specific focus on ambient pressure X-ray photoelectron and absorption techniques such as near and extended X-ray absorption fine structure. Each of the techniques is evaluated, whilst the pros and cons are discussed in term of surface sensitivity, spatial resolution and/or time resolution. The second part of the articles is articulated around the future of in situ characterization, giving examples of the probable development of the discussed techniques as well as an introduction of emerging tools such as scanning transmission X-ray microscopy, ptychography, and X-ray photon correlation spectroscopy

Adsorption site of alkanes on metals and associated hydrogen pressure effects

A series of arguments, based on experimental results concerning mainly methane and ethane, in favour of an associative mechanism of the hydrocarbon with an adsorbed H atom for the adsorption step of alkanes on metal surfaces are reviewed. The reaction scheme for the adsorption step is written: {A figure is presented} As w has a smaller value than z, a coverage function in hydrogen, of the type (1-θH)Z if the adsorption step is rate determining, or (1-θH)Z-W if the adsorption step is near to equilibrium, contributes to the kinetic equation of the catalytic reaction. Due to the large value of z (8 or more), this function contains a hydrogen pressure and a temperature dependence of the same type as measured on the rate of the catalytic reaction. It also contains a demanding character. © 1992.SCOPUS: ar.jinfo:eu-repo/semantics/publishe