About the depth sensitivity of second-harmonic radiation in ultra-thin metal films

Second-harmonic generation (SHG) results for Ni and Co films on Cu (001) have been reinvestigated regarding the depth sensitivity of this technique for thin films. We find that tangential components of the nonlinear susceptibility are much more sensitive to real film properties than normal components, which are confined to surfaces and interfaces. In consequence, for SHG experiments on ultra-thin metal films, polarization combinations should be favored that possess only tangential susceptibility components, even though the yield is weaker. Additional phase measurements are necessary to obtain full information about the film. Received: 20 January 2002 / Published online: 6 June 2002