Beneficial effect of heating on the morphology and second-order nonlinear optical efficiency of anisotropic thin films

In this Letter we describe the effect of heating on the quality, morphology and nonlinear optical efficiency of anisotropic Langmuir-Blodgett films co mposed of a chiral helicenebisquinone derivative. The samples were studied with second harmonic generation (SHG), UV-Vis absorption spectroscopy and a tomic force microscopy (AFM). Heating a Langmuir-Blodgett film of a helicen ebisquinone derivative improves the film quality (homogeneity, surf;tce smo othness). In addition, it increases the film's anisotropy and, as a consequ ence doubles its nonlinear optical efficiency. (C) 2000 Elsevier Science B. V. All rights reserved.