Hp. Lang et al., AMORPHIZATION OF C-60 FULLERITE BY APPLYING PRESSURE IN THE GPA RANGEUSING A SCANNING TUNNELING MICROSCOPE - OBSERVATION OF TRANSITIONS AND AGING, Journal of physics and chemistry of solids, 58(11), 1997, pp. 1757-1761
Fullerene molecules of a few monolayers thick C-60(111) film on Au(111
) supported on mica, have been exposed to a pressure of approximate to
20 GPa by using the tip of a scanning tunneling microscope (STM) oper
ated at 40 nA and 4 mV. Subsequent imaging at 0.7 nA and - 11 mV shows
that this pressure has induced a transformation of C-60 fullerite int
o an amorphous structure with a nearest neighbour distance of 0.28 nm.
The time evolution of this structure within approximate to 90 min rev
eals formation of nanocrystalline domains, their transformation into s
quare eight-membered closed ring structures, and the breaking-up of th
ese rings initially zig-zag, and then finally straight chains. Assignm
ent of pentagon and hexagon carbon rings to the observed arrangements
of protrusions is a possible explanation. Pair distribution and angula
r distribution functions are calculated based on the position of the p
rotrusions extracted from the images. (C) 1997 Elsevier Science Ltd.