DIRECT OBSERVATION OF EPITAXIALLY GROWN C-60 CRYSTALS AND MOLECULES ON VACUUM-DEPOSITED MGO FILMS

Epitaxially grown crystals of C-60 are prepared on (001) vacuum-deposi ted MgO films by successive deposition of MgO and C-60 on a heated NaC l(001) cleaved surface. C-60 grows as single-crystalline triangular is lands with fee structure on the MgO films from 180 to 200 degrees C. T he epitawial relations are (111)[110](C60)//(001)[010](C60) and (111)[ 110](C60)//(001)[100](C60) as a result of Volmer-Weber growth. The isl ands do not have twin-like defects like those of C-60 crystals previou sly grown on NaCl(001) substrates. High-resolution electron microscopy shows the images of aggregates of C-60 molecules as ring-like black c ontrast at the edge of islands prepared at room temperature and 180 de grees C. Image simulations of one C-60 molecule located on MgO crystal s of 10 and 20 nm thickness are presented, and the possibility of dete ction of the molecule is discussed in relation to the use of imaging u nder off-Bragg condition.