EXPERIMENTAL RESEARCH INTO THE EFFECTS OF INTERFACE ROUGHNESS IN MULTILAYERS ON NEUTRON REFLECTION AND TRANSMISSION

The effects of interface roughness for several multilayers are evaluat ed from measurements of neutron reflectivity and transmissivity as a f unction of momentum transfer, together with the profiles of the reflec ted and transmitted neutron beams. The multilayers are fabricated by v acuum evaporation onto polished Si substrates, whose roughness is meas ured with another optical technique. The multilayer samples are: (1) N i/Ti with a period of 100 Angstrom, and 100 layers evaporated on a rou gh Si substrate, (2) a Ge/Ti multilayer with 36 layers and a 200 Angst rom period evaporated on sample 1, (3) a Ni/Ti multilayer with 52 laye rs and a 100 Angstrom period on a smooth Si substrate, and (4) a V/Ti multilayer with 8 layers and a 400 Angstrom period on a smooth Si subs trate. The neutron measurements are carried out using a reflectometer at JRR-3M at JAERI. The reflectometer is a theta - 20 scanning-type us ing a 12.6 Angstrom neutron beam. The comparison between the experimen tal neutron reflectivity with that calculated using a one-dimensional optical method with a modified optical potential is also discussed.