Fig. 4
Multichromatic change and whiteout effect by water film formation. a Schematic illustrations describing water-film formation on β-phase PdHX surface. b Time-lapse photographs of the FP etalon under 10% H2 followed by 20% O2 exposure. c Measured reflection spectra as a function of O2 concentrations (0–20%) at β-phase PdHX surface (red-dashed area of b). d Sampled reflection spectra (each color matches to dashed lines in c). e CIE 1931 color map of the FP etalon depending on tBPVE (400–1200 nm) (circles for simulation and ‘X’ for experimental results from d). Scale bar, 2 cm