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Orientational Ordering and Intermolecular Interactions in the Rotor-Stator Compounds C-60 center dot C8H8 and C-70 center dot C8H8 Studied under Pressure

Thirunavukkuarasu, K.

Kuntscher, C. A.

Nagy, B. J.

Klupp, Gyöngyi

Kamarás, Katalin

Kováts, Éva

Pekker, Sándor

American Chemical Society

2008

QC Physics / fizika

QC06 Physics of condensed matter / szilárdtestfizika

QD Chemistry / kémia

Pressure-dependent transmittance measurements on C-60 center dot C8H8
and C-70 center dot C8H8 at room temperature were performed for
pressures up to 10 GPa in the mid- and near-infrared frequency range,
in order to monitor the vibrational modes of the fullerene and cubane
molecules as a function of external pressure. Furthermore, the position
of the absorption edge related to intramolecular electronic excitations
on the fullerene molecules was studied with increasing pressure. For
C-60 center dot C8H8, the anomaly at 0.5 GPa in the pressure dependence
of the vibrational modes indicates a pressure-induced orientational
ordering transition of the fullerene molecules and the anomaly at 1.3
GPa can be related to fullerene-cubane interaction. In C-70 center dot
C8H8, the pressure-induced changes are more pronounced, with a
splitting of the cubane modes at the pressures 0.8 and 1.75 GPa. This
finding indicates stronger intermolecular interactions in C-70 center
dot C8H8 compared to C-60 center dot C8H8, leading to larger
distortions of cubane molecules. The energy position of the absorption
edge in C-60 center dot C8H8 and C-70 center dot C8H8 shows a nonlinear
decrease with increasing pressure. The zero-pressure value of the
absorption edge in C-60 center dot C8H8 is larger than that of pristine
C-60 indicating that the cubane molecules reduce the overlap of the
C-60 molecular orbitals. In C-70 center dot C8H8, no shift of the
optical absorption edge relative to C-70 is found, in agreement with
this compound being closer to a host-guest system than C-60 center dot
C8H8.

Article

PeerReviewed

text

http://real.mtak.hu/6075/1/1170157.pdf

Thirunavukkuarasu, K. and Kuntscher, C. A. and Nagy, B. J. and Klupp, Gyöngyi and Kamarás, Katalin and Kováts, Éva and Pekker, Sándor (2008) Orientational Ordering and Intermolecular Interactions in the Rotor-Stator Compounds C-60 center dot C8H8 and C-70 center dot C8H8 Studied under Pressure. JOURNAL OF PHYSICAL CHEMISTRY C - NANOMATERIALS AND INTERFACES, 112 (45). pp. 17525-17532. ISSN 1932-7447

http://real.mtak.hu/6075/