Electrical XPS meets biology: in situ chemo-electrical sensing and activation of organic materials

Abstract

X-ray photoelectron spectroscopy (XPS) is a popular analytical technique in materials sciences owing to its versatile coverage of broad energy ranges and the reliability of its quantitative compositional analysis. Hence, tailoring XPS capabilities to the research frontiers of biological systems and nature-inspired materials can potentially be of great value. However, the application of XPS in bio/organic systems encounters critical inherent challenges, specifically amplified by the rich nuances that are at the heart of biological functions. The present mini review describes some of these difficulties, showing that by combining electrical-sensing capabilities in situ with standard XPS chemical analysis, diverse and effective solutions can be achieved. A related method, termed chemically resolved electrical measurements (CREM), is described, and case study examples are provided, ranging from self-assembled monolayers of small molecules to relatively large supramolecular sugars and proteins. A detailed discussion is dedicated to specimen stability issues, charge capturing and hot-charge transport functionalities, for which the CREM approach provides particularly attractive capabilities and a template for advanced characterization strategies.