Probing the solid–liquid interface with tender x rays: a new ambient-pressure x-ray photoelectron spectroscopy endstation at the Swiss Light Source

Abstract

A new endstation to perform operando chemical analysis at solid–liquid interfaces by means of ambient pressure x-ray photoelectron spectroscopy (APXPS) is presented. The endstation is located at the Swiss Light Source and can be attached to the soft x-ray in situ spectroscopy beamline (X07DB) for solid–gas type experiments and to a tender x-ray beamline (PHOENIX I) for solid–liquid interface experiments. The setup consists of three interconnected ultrahigh vacuum chambers: one for sample preparation using surface science techniques, the analysis chamber for APXPS experiments, and an entry-lock chamber for sample transfer across the two pressure regimes. The APXPS chamber is designed to study solid–liquid interfaces stabilized by the dip and pull method. Using a three-electrode setup, the potential difference across the solid-electrolyte interface can be controlled, as is demonstrated here using an Ir(001) electrode dipped and pulled from a 0.1M KOH electrolyte. The new endstation is successfully commissioned and will offer unique opportunities for fundamental studies of phenomena that take place at solid–liquid interfaces and that are relevant for fields such as electrochemistry, photochemistry, or biochemistry, to name a few.