title: Direct spectroscopic evidence of the mechanism behind the phase transition of [2,2]-paracyclophane.
abstract: [2,2]-Paracyclophane undergoes phase transitions at 45 and 60 K. Based on simultaneous Raman spectroscopy and inelastic neutron scattering experiments (12-70 K), it was shown that a twisting motion of the ethylene bridge perpendicular to the plane of the aromatic rings drives the phase transition. The low-temperature (<45 K) and high-temperature (>60 K) conformers only differ by this twisting motion, which freezes out below 45 K and is thermally averaged above 60 K. Between 45 and 60 K, the system gains energy until the phase transition is complete.
authors: Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany), Fax: (+49) 551-39-33459.
authors: Hilke
authors: H
authors: Wolf
authors: Nina
authors: N
authors: Lock
authors: Stewart F
authors: SF
authors: Parker
authors: Dietmar
authors: D
authors: Stalke
keywords: Raman spectroscopy; inelastic neutron scattering; non-destructive phase transition; paracyclophane; structure determination