Core level photoemission evidence of frustrated surface molecules: a germ of disorder at the (111) surface of C60 before the order-disorder surface phase transition.
Using high resolution core level photoemission, we investigated the disordering transition of the fullerene molecules at the (111) surface of C (60) films. The experimental evidence of a two-step mechanism for the rotational disordering of surface fullerene molecules is provided. The data are consistent with a recent model in which the rotational degrees of freedom of one molecule, out of the four inequivalent C (60) molecules of the low temperature (2x2) surface unit cell, melt about 100 K before the bulk phase transition.
Goldoni
A
A
Sincrotrone Trieste S.C.p.A., strada statale 14 Km 163.5 in Area Science Park, 34012 Trieste, Italy. goldonia@elettra.trieste.it
Cepek
C
C
Larciprete
R
R
Sangaletti
L
L
Pagliara
S
S
Paolucci
G
G
Sancrotti
M
M