ELLIPSOMETRIC RESPONSE TO HYDROGEN ADSORPTION ON THIN IRON FILMS

We report on measurements of the dielectric function of thin iron films deposited on glass substrates under uhv conditions and subsequently covered with hydrogen at 77 K as well as the 293 K. Hydrogen adsorption at 77 K causes the ellipsometrical parameters delta-DELTA and delta-psi to increase by 0.1-degrees and 0.03-degrees, respectively. At 293 K the delta-psi values slightly decrease (lambda = 1152 nm). The results are discussed on the basis of a three-layer model based on the extrapolated macroscopic theory.