Two-dimensional crystal of several millimeter size spheres

Two-dimensional crystal is tested in the system of several millimeter size polystyrene spheres. Large numbers of same size spheres are triboelectrical ly charged through rubbing on the substrate plate. Therefore, one can obser ve the two-dimensional system without the help of any instrument and can ea sily micro-control the condition of two-dimensional system. The Fourier tra nsform spectra, the pair distribution and the bond-orientational correlatio n function data show that the system is in near hexatic phase after fully c harged, which is predicted by the KTHNY theory. (C) 2000 Elsevier Science B .V. All rights reserved,