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O: Fachverband Oberflächenphysik

O 45: Mini-Symposium: Molecular scale investigations of liquid-vapor interfaces I

O 45.2: Talk

Tuesday, March 2, 2021, 14:00–14:20, R3

A Flow-Focused Droplet Train for Investigating Liquid Phase Processes with Ambient Pressure XPS — •Pip Clark, Michael Sear, Marco Favaro, Roel van de Krol, and David Starr — Institute for Solar Fuels Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany

Here we present a newly commissioned droplet train designed for measuring the chemical and physical properties of liquids in pressures up to 30 mbar using ambient pressure XPS. Our droplet train generates thousands of uniform droplets a second, tunable in diameter between 100 to 500 microns.

We present results from commissioning experiments on aqueous solutions and colloidal systems, and describe the advantages of using flow focusing. We also discuss the capability of time-resolved XPS using the droplet train. By changing the height of the droplet generation point above the spectroscopic analysis position and introducing a suitable time-zero trigger, different delay times can be measured. Depending on the speed of the droplets chosen, we can access delay times between tens of μs and hundreds of ms. Examples of possible systems to study include (but are not limited to) gas uptake at the liquid/vapor interface, photoinduced physical and chemical reactions in solution, and nucleation and growth of salt crystallites or nanoparticles.

The droplet train module is a part of the SpAnTeX end station, which focuses on AP-XPS experiments in the tender X-ray regime (AP-HAXPES). Commissioning experiments were performed at the KMC-1 beamline, at BESSY II in Berlin.