Determination of molecular orientation by angular dependence of second harmonic intensity and second harmonic phase measurements

Thin films of 2-docosylamino-5-nitropyridine (DCANP) deposited by Langmuir- Blodgett technique on silicon and quartz glass substrate have been investig ated by means of spectroscopic ellipsometry and second harmonic generation (SHG). It was found that the selected substrate had a non-significant influ ence on the determined second order susceptibility. By measuring the angula r dependence of the reflected second harmonic generation signal with a prop er combination of input and output polarization all independent elements of the second order susceptibility tensor have been determined. The importanc e of Fresnel field correction factor is discussed. It is illustrated that p hase measurements of SHG allow the determination of the sign of the net dip ole moment with respect to the substrate plane. (C) 2000 Elsevier Science B .V. All rights reserved.