Comprehension of the effects of proton on reflectivity of Mo/Si multilayer

Wavelength dependent reflectivity is crucial relationship in determining the physical property of optic system. The first object of this work is to search for the applicable method of using wavelength to predict the reflectivity of Mo/Si multilayer mirror before and after irradiation with proton. Predicated on the principle of non-linear curve fitting, a typical numerical method is highlighted because the wavelength-dependent reflectivity of Mo/Si multilayer irradiated by proton with different energies and flux are quantitative analyzed by this method. The simulations agree very well with the observed spectroscopy of 6 curves for reflectivity versus wavelength. The minimum value of correlation coefficients between actual and calculated data is 0.994. The other objects of this work are to find the optic band gap of Mo/Si multilayer and check the influences of proton on it using reflectivity spectra. In the light of the calculated results by Tauc method, the optic band gap is theoretically explained successfully via the relationship between band gap and absorption coefficient. The estimated results by both theoretical and experimental data demonstrate that the optic band gap of Mo/Si multilayer is not sensitive to proton radiation.