Localized oscillations and Fraunhofer diffraction in crystalline phases ofa monolayer

Localized oscillations present in the crystalline phases of the heneicosano ic acid Langmuir monolayer were studied in detail. They appear like blinkin g interference rings, when observed with Brewster angle microscopy. Monolay ers with localized oscillations were transferred on mica to be characterize d by atomic force microscopy. We found granules produced by the expulsion o f matter from the monolayer. However, these granules are too short to produ ce Newton's rings; the common belief of the origin of the interference ring s in the field of Langmuir monolayers. The analysis of the light intensity distribution and the sizes of the rings are consistent with Airy patterns p roduced by Fraunhofer diffraction due to the reflected light from the multi layer granules. The origin of the blinking of these patterns is still uncle ar. (C) 2001 American Institute of Physics.