ENHANCEMENT OF THE REFLECTIVITY OF SOFT-X-RAY CO C MULTILAYERS AT GRAZING-INCIDENCE BY THERMAL-TREATMENT/

We report a significant increase in the reflectivity of a soft x-ray C o/C multilayer at grazing incidence after low-temperature annealing. B y monitoring the enhancement of the first-order modulation peak on ann ealing, an effective interdiffusion coefficient as low as -10(-25) m(2 ) s(-1) has been measured, which is nearly equal to the true macroscop ic interdiffusion coefficient as the modulation wavelength of the Co/C multilayer studied is well above the critical wavelength. The negativ e true macroscopic interdiffusion coefficient indicates that there is a tendency to phase separation in the Co-C system, which can be interp reted as the positive enthalpy of mixing calculated on the basis of Mi edema's macroscopic atom model. The decrease in reflectivity above som e annealing temperature is also discussed and explained as the competi tion between interfacial sharpness and roughness. This is the first re port of observations of enhanced reflectivity in the Co/C multilayered system.