Local dynamics in polymer-dispersed liquid crystals studied by near-field scanning optical microscopy

Electric-field-induced molecular reorientation dynamics are studied in loca lized regions within polymer-dispersed liquid-crystal (PDLC) films, using t ime-resolved near-field scanning optical microscopy (NSOM) methods. A conce ntrated electric field is applied across the PDLC film, between the metalli zed NSOM probe and the conductive, transparent substrate supporting the sam ple. The electric field is modulated as a square wave form at (sub)-kiloher tz frequencies. Subsequent liquid-crystal (LC) reorientation is observed by crossed-polarized, transmitted-light NSOM methods. The results show dramat ic spatial variations in the time scale over which the molecules reorient. The variations are interpreted based on proximity of the region probed to t he polymer-LC interface. (C) 1998 American Institute of Physics. [S0003-695 1(98)01250-9].