Evidence of the Jahn-Teller splitting ofC60−inC60

Abstract

Pulsed EPR measurements of the transverse and longitudinal relaxation times of the C« -anion radical in crystalline C«-tetraphenylphosphoniumchloride were done at temperatures from 4 to 40 K. Above 40 K to room temperature the longitudinal relaxation time was taken from the cw-EPR linewidth. The low-temperature data are explained in terms of local magnetic fluctuations, slow C«motion, and localized two-level states related with the local disorder. The relaxation data at higher temperatures reveal experimental evidence for the Jahn-Teller distortion of the C6p -anion radical and allow to determine the Jahn-Teller splitting between the az"electronic ground state and the excited el"state of the unpaired electron.

Discrete Fulleride Anions and Fullerenium Cations

“…Rather, low-lying states contribute to the line width of the broad signal via Orbach relaxation. 350 In 1995, Huang and co-workers made a related proposal that C 60 -could exist in two different ground states depending on ion-pairing effects. 322 They observed that the relative intensity of the sharp versus broad signal in KC 60 ‚THF increased as the solvent was removed under vacuum.…”

“…346 A more quantitative understanding of the broad, temperature-dependent signal is coming from pulsed EPR measurements of the traverse and longitudinal relaxation times of C 60 -in a tetraphenylphosphonium salt. 350 Its origin clearly lies in the dynamic nature of the small Jahn-Teller distortion associated with degeneracy of the (t 1u ) 1 ground state. This gives rise to a 2 A ground state and a close lying 2 E excited state 179 which can give rise to signal broadening by an Orbach relaxation process.…”

Far-infrared study of the Jahn-Teller-distortedC60monoanion inC60Long1, Musfeldt2, Schilder3 et al. 1998Phys. Rev. B255391View full textAdd to dashboardCite

“…Thus, we supplement the vibrational studies reported to date 8,9,12,16 and complement the previous EPR temperature dependence work. 6,11,31 …”

“…6,11,30 Pulsed EPR measurements on the chloride-containing salt show Orbachtype spin-lattice relaxations, consistent with JT vibronic excitations. 31 ͑Ph 4 P͒ 2 IC 60 can be compared to other solid-state fullerene materials with regards to the charge and symmetry states of the ball and the degree of separation between balls. The A n C 60 alkali-metal doped fullerides contain the negatively charged C 60 ball (chargeϭn) which is subject to a JTE for 1рnр5.…”

Investigation of the Jahn–Teller effect in the ${\rm C}_{60}^{{-} } $ monoanion under high pressure

“…Near infrared-visible spectroscopic experiments on (Ph 4 P) 2 IC 60 show that the electronic and vibrational properties of the C À 60 anion are hardly perturbed by the counterion environment [6]. Detailed temperaturedependent studies of (Ph 4 P) 2 IC 60 have been carried out by electron paramagnetic resonance (EPR) [4,7,8], Raman scattering [9], and infrared spectroscopy [10,11], which demonstrate the dynamic JT effect at room temperature. During cooling down (Ph 4 P) 2 IC 60 undergoes a transition to a static JT distorted state in the temperature range 120-140 K.…”