Hydrogenation dynamics of Ru capped Y thin films.

The structural changes in Ru-coated Y films during hydrogenation were studied in this work. In situ XRD data were used to show that the Y to YH₂ transition requires significant hydrogen loading of the Y lattice. By comparing the XRD data with the in situ spectroscopic ellipsometry data, an effective medium model for the transition was obtained. This model describes the Y to YH₂ transition well. The YH₂ to YH₃ transition is also described by an effective medium model, however, with reduced accuracy around the midpoint of the transition. By comparing the YH₂ and YH₃ crystal sizes, we show that these deviations may be due to a surface plasmon resonance. The improved understanding of the ellipsometry measurements is important for optical hydrogen sensing applications. [ABSTRACT FROM AUTHOR]