Hyper-Rayleigh scattering from Langmuir films of C60 and its derivatives

Hyper-Rayleigh scattering (HRS), or incoherent second-harmonic generation, from Langmuir films of C-60 and its derivatives deposited upon fused-quartz substrates is studied experimentally. For C-60 and C-60-tetracyanoethylene oxide derivative (C-60([CN])) films the diffuse second-harmonic signal from a single Langmuir layer is at least ten times larger than that from multilayer films. For C-60-indopane derivative (C-60([ind])) films no peculiarities in the diffuse second-harmonic signal from a single layer are observed, whereas the ratio of the intensities of specular and diffuse signals is found to be proportional to the thickness of the film. HRS indicatrices are measured; the results yield estimates for the correlation length of fluctuations of nonlinear polarization: 100 nm for C-60 and C-60([CN]) films and 300 nm for C-60([ind]) films. (C) 1999 Optical Society of America [S0740-3224(99)03309-3].