of the excitation laser beam were 150 fs, 400 nm, and 1 kHz, respectively. The excitation energy can be varied within the range from 0.01 to 28 lJ pulse ±1 . The illumination area on the sample was about 0.2 mm 2 . The excitation laser beam irradiated the sample at an angle of 45 with respect to the cell plate normal. The emission spectra from the dye-doped FLC were measured from the opposite side of the cell using a spectrograph (Oriel, MS257) with a charge coupled device (CCD) detector having spectral resolution of 0.3 nm. The collecting direction was perpendicular to the cell surface, which is normal to the smectic layers and along the helical axis. The preparation of semiconductor and metal nanoparticles has been extensively studied and many new optoelectronic properties, such as quantum confinement and finite size effects, have been discovered, and prospective applications have been developed.
Received[1] However, little attention has been paid to the fabrication of organic nanoparticles, probably due to their thermal instability and weak mechanical properties. Recently, several researchers have revealed size-tunable optoelectronic properties of organic nanoparticles and their high potential for novel electronic devices. In the case of organic compounds, their electronic and optical properties are fundamentally different from those of semiconductors and metals due to their weak (van der Waals) intermolecular interactions [2,3] and the small radius of the Frenkel exciton.