Identifying Trends in the Field Ionization of Diatomic Molecules over Adsorbate Covered Pd(331) Surfaces
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ORIGINAL PAPER
Identifying Trends in the Field Ionization of Diatomic Molecules over Adsorbate Covered Pd(331) Surfaces Alyssa J. R. Hensley1 · Ian deJoode2 · Yong Wang1,3 · Jean‑Sabin McEwen1,2,3,4,5 Accepted: 9 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Capturing the dynamic fluctuations in structure and adsorbate coverage on catalytic surfaces under operating conditions is of critical importance to the identification of active sites and subsequent design of materials for targeted bond activation but remains challenging to achieve both experimentally and computationally. Field ion microscopy achieves such in situ reaction monitoring on single catalytic grains via applied electric fields which ionize atmospheric gases at the surface, providing images of the working catalyst surface. However, such images remain difficult to deconvolute without simplifying assumptions. Here, we use density functional theory to probe the mechanism for field ionization of a series of imaging gases (O2, N2, and NO) over oxygen, nitrogen, sulfur, and carbon covered Pd(331). From this dataset of field ionization systems, we determined that the primary factors affecting field ionization are the relative energy levels for the imaging gas’s occupied states and the surface’s unoccupied states, both of which are tunable through choice of imaging gas and the presence of adsorbates, respectively. Using such quantitative descriptors of the electronic accessibility of both the imaging gas and adsorbate covered surface, we develop a predictive tool for the rapid assessment of any system’s field ionization potential. Overall, this work provides fundamental insight into the field ionization mechanism and presents an easy-to-use predictive tool that can assist with both the analysis of existing field ion microscopy images and the design of future experiments. Keywords Field ion microscopy · Descriptor-based model · Resonant field ionization · Density functional theory · Palladium
1 Introduction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11244-020-01392-y) contains supplementary material, which is available to authorized users. * Jean‑Sabin McEwen [email protected] 1
The Gene and Linda Voiland, School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
2
Department of Chemistry, Washington State University, Pullman, WA 99164, USA
3
Pacific Northwest National Laboratory, Institute for Integrated Catalysis, Richland, WA 99352, USA
4
Department of Physics and Astronomy, Washington State University, Pullman, WA 99164, USA
5
Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA
The in situ detection of reactive adsorbates and surface reconstruction under catalytic conditions remains a highly sought after goal both experimentally and computationally as the desired active sites are often not present at any other time [1–3]. One possible tool t
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