Design and testing of an (inert) gas cell for in situ polarization modulation infrared reflection absorption spectroscopic (PM-IRRAS) measurements under specific atmospheres.

This article focuses on the design, construction, and application of a new inert gas cell integrated with a commercially available polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) module (Bruker PMA50) for studying air-sensitive molecular monolayers on metal surfaces. The gas cell enables measurements under controlled gaseous atmospheres, including inert conditions, by allowing sample transfer into a glovebox and gas flow regulation via two hose connections, while also permitting light irradiation through a dedicated window. Using this setup, the authors successfully characterized the oxygen-sensitive conversion of a molybdenum(0) tricarbonyl complex adsorbed on Au(111) to its molybdenum(VI) trioxo analog, demonstrating in situ and time-dependent monitoring of the reaction both thermally and under UV/visible light irradiation. The cell offers a cost-effective, easy-to-use alternative to ultra-high vacuum systems, though it is less leak-tight and limited to room-temperature measurements.