Enabling temperature controlled in-situ vapor dosing for lab source X-ray reflectivity measurements

Abstract

X-ray Reflectivity (XRR) is a valuable technique for probing buried interfaces in complex systems relevant to thin-film, membrane, and battery applications, among others. However, many operando and in situ reflectivity cells are designed for use at synchrotron facilities, limiting the broader accessibility of these measurements. We present an XRR transmission cell that enables in situ vapor dosing and temperature-dependent experiments on in-house diffractometers. We demonstrate its capabilities with two case studies: the adsorption of water into polyamide (PA) membranes on silicon and temperature-dependent restructuring of polystyrene (PS) pseudo brushes on alumina. Vapor dosing allows for controlled release of vapor into the cell, allowing operation across a wide range of conditions from rough vacuum to saturation. We demonstrate that the manifold can reach 90-95% of saturated pressures, with the measurements presented here spanning 0-250 mbar, which is desirable for adsorption isotherms. Heating studies performed between 25 and 200C demonstrate the ability to resolve Ångstrom scale structural changes in a surface bound polymer. These results establish a novel streamlined approach to temperature controlled vapor dosing on a laboratory diffractometer, offering straightforward probe-molecule exchange, vacuum-sealed operations, and variable temperature capabilities.