Abstract

SHG and THG signals were observed by reflection from the Langmuir-Blodgett monolayer of a Sec-butyl derivative of 4-methyl-6-nitro-2-quinolinamine. A floating monolayer was obtained by spreading chloroform solutions on ultrapure water and the subsequent evaporation of chloroform. The monolayer was deposited on a suitably treated glass slide at a compression rate of 100 cm²/min and a pressure of 12 mN/m. The 1064 nm fundamental wave emanating from a Nd:YAG laser was incident at a 45° angle on the monolayer surface, with the length of the substrate in a vertical plane. Signals were observed at 532 nm (SHG) and 355 nm (THG). When the sample was rotated by 90° in a vertical plane, the SHG signal vanished and the THG signal became much smaller. SHG and THG signals were also observed by reflection from a L-B film of 20 monolayers. When this sample was rotated by 90°, there was no significant difference in the intensity of the signals. The values of χ² and χ³ were determined to be 10⁻⁶ and 5 × 10⁻⁴ esu, respectively, by using standard relations.

© 1992 Optical Society of America