Enabling correlative micro-spectroscopy with total reflection X-ray fluorescence via surface-functionalized sample preparation

Abstract

Total reflection X-ray fluorescence (TXRF) spectroscopy is a powerful trace elemental analysis technique and as such would be a highly valuable addition to a correlative micro-spectroscopic analysis workflow for full sample characterization. Successful integration of TXRF into such workflows, however, critically depends on sample preparation. In this work, we present a robust and versatile sample preparation strategy specifically aimed for application in complementary micro- and spectroscopic methods. The analyte was deposited on the TXRF reflector with spatial control achieved by means of functionalizing the reflector with well-defined hydrophobic and hydrophilic areas. Additionally, Marangoni drying was applied to improve the analyte homogeneity within the functionalized areas, which was confirmed by laser scanning confocal fluorescence microscopy. Subsequent TXRF measurements demonstrated that all target elements (C, Sc, and Ti) were localized within the same spot. Importantly, Ti could be quantitatively determined under all experimental conditions. Overall, the developed methodology provides enhanced control over TXRF sample preparation, particularly for complex systems, and supports the effective use of TXRF within correlative micro-spectroscopic approaches. The method presented here is simple to implement, cost-effective, highly adaptable, and applicable to a wide range of reflector materials and analytes.