Integrated laser heating stage with active geometry modulation for simultaneous in-situ X-ray transmission and evolved gas analysis of molten liquids

Abstract

We report the design and development of a compact, integrated laser heating stage tailored for in situ high-temperature X ray transmission studies of molten oxides. In horizontal beam geometries, widely used in both laboratory and synchrotron facilities, the natural spreading (wetting) of molten samples on substrates significantly reduces the effective vertical optical path length, detrimental to signal quality in transmission-mode measurements. To overcome this limitation, we introduced a thermocouple assisted active geometry modulation technique. This method mechanically lifts the spreading melt into a liquid bridge via surface tension, optimizing the transmission path length while simultaneously enabling in situ temperature monitoring. The device features a triple fiber coupled laser head with high power density, a precision closed loop Proportional Integral Derivative temperature control system, and an atmosphere controlled vacuum chamber coupled with a mass spectrometer. This integration allows for simultaneous evolved gas analysis, enabling the correlation of structural phase transitions with chemical volatilization or reaction dynamics. Validated by tracking the melting kinetics of a multicomponent glass precursor, this versatile setup provides a comprehensive solution for high quality data acquisition in X ray transmission experiments across various sources.