Far-infrared study of C60-tetraphenylphosphoniumiodide

Long, Van Cao; Musfeldt, J. L.; Schilder, A.; Schütz, Wilhelm

doi:10.1016/s0379-6779(98)00714-0

Cited by 5 publications

(14 citation statements)

References 9 publications

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“…These states are connected through a movement called pseudorotation, which causes the disorder in the dynamic system. In agreement with our data, the room-temperature dynamic JT effect has been reported by FIR temperature-dependent studies [10,11]. The other significant mode observed in our measurements is the G u (1) mode, which shows no splitting at ambient conditions.…”

Section: High-pressure Infrared Measurementssupporting

confidence: 93%

“…This finding suggests a splitting of the G u (1) mode into at least two modes at around 2 GPa (see Fig. 4 for frequencies), consistent with temperature-dependent infrared studies on (Ph 4 P) 2 IC 60 which revealed a doublet splitting of the G u (1) mode at 150 K [10,11]. According to group theory, a two-fold splitting of the G u (1) mode is expected as the system settles down for D 3d (or lower) symmetry.…”

Section: High Pressuresupporting

confidence: 85%

“…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.…”

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confidence: 99%

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

Francis

Scharinger

Németh

et al. 2010

Physica Status Solidi (b)

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We report the Jahn-Teller (JT) dynamics of the C À 60 monoanion under pressure in (Ph 4 P) 2 IC 60 . (Ph 4 P) 2 IC 60 was synthesized by electrochemical crystallization and investigated by infrared transmission measurements up to 5 GPa. The behavior of two T 1u vibrational modes of C À 60 , which exhibit signatures of the dynamic JT effect at ambient conditions, was followed under pressure. The pressureinduced transition from the dynamic to the static JT state was observed at $2 GPa. Due to symmetry lowering related to the dynamic JT effect, the G 1u mode is activated and shows a splitting at the pressure-induced dynamic-to-static JT distortion. 1 Introduction C 60 -fullerene, the highly symmetric system in nature has kindled interest among the scientific community, to investigate its intriguing properties. The neutral C 60 molecule crystallizes in face-centered cubic (fcc) structure at room temperature and has large enough interstitial space for doping with alkali metals. Several fullerene-related compounds were synthesized and have been investigated. With appropriate doping, the properties of C 60 can be tuned from insulating to superconducting state or even magnetic. Doping C 60 with electrons induces interesting properties in the corresponding compounds: metallic superconducting phases A 3 C 60 (where A stands for alkali metal), semiconducting A 4 C 60 or ferromagnetic TDAE-C 60 which are governed by various physical phenomena [1,2].(Ph 4 P) 2 IC 60 (C 60 -tetraphenylphosphoniumiodide) is one of the charge transfer salts, synthesized by electrochemical method [3]. This fully ionic (Ph 4 P) 2 IC 60 is air stable. (Ph 4 P) 2 IC 60 is tetragonal with space group I 4/m . The I 4/m space group sustains two geometrically equivalent orientations of the C

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Section: High-pressure Infrared Measurementssupporting

confidence: 93%

Section: High Pressuresupporting

confidence: 85%

mentioning

confidence: 99%

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

Francis

Scharinger

Németh

et al. 2010

Physica Status Solidi (b)

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“…The temperature dependence of the JT dynamics was studied on these compounds by far-infrared spectroscopy. [5][6][7][8][9][10][11][12] Another experimental evidence for the dynamic nature of the JT effect in [(Ph 4 P) 2 IC 60 ] was obtained by ESR, [8][9][10][11][12] 1: Crystal structure of (Ph4P)2IC60. [2][3][4] above 40 K through an Orbach spin-lattice relaxation process.…”

Section: Introductionmentioning

confidence: 96%

“…[2][3][4] At room temperature, the dynamic nature of the Jahn-Teller (JT) effect in (Ph 4 Y) 2 XC 60 (Y = P or As, X = Cl, I, or Br) was shown by electron spin resonance (ESR), nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy. [5][6][7] Theoretically, the dynamic JT effect for singly charged fullerene C − 60 is expected to be reflected in the IR spectrum. At room temperature, the dynamic disorder between different orientations of the C − 60 is signalled in the infrared spectrum by the splitting of the T 1u fundamental modes of fullerene and the activation of silent modes.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced transition from the dynamic to static Jahn-Teller effect in (Ph4P)2IC60

et al. 2012

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High-pressure infrared transmission measurements on (Ph4P)2IC60 were performed up to 9 GPa over a broad frequency range (200 -20000 cm −1 ) to monitor the vibrational and electronic/vibronic excitations under pressure. The four fundamental T1u modes of C − 60 are split into doublets already at the lowest applied pressure and harden with increasing pressure. Several cation modes and fullerene-related modes split into doublets at around 2 GPa, the most prominent one being the G1u mode. The splitting of the vibrational modes can be attributed to the transition from the dynamic to static Jahn-Teller effect, caused by steric crowding at high pressure. Four absorption bands are observed in the NIR-VIS frequency range. They are discussed in terms of transitions between LUMO electronic states in C − 60 , which are split because of the Jahn-Teller distortion and can be coupled with vibrational modes. Various distortions and the corresponding symmetry lowering are discussed. The observed redshift of the absorption bands indicates that the splitting of the LUMO electronic states is reduced upon pressure application.

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Vibrational Assignment of All 46 Fundamentals of C₆₀ and C₆₀^6-: Scaled Quantum Mechanical Results Performed in Redundant Internal Coordinates and Compared to Experiments

1999

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Traditional vibrational assignment in terms of bond stretching, angle bending, and torsion is not possible in fullerenes due to the very large number of coupled internal coordinates. Large scale density functional calculations of the vibrational properties of C 60 and C 60 6have been carried out with Becke3LYP and BeckeLYP exchange-correlation functionals in the pursuit of obtaining a reliable set of 174 normal modes (46 fundamental frequencies) and understanding the effect of charge transfer (doping) on the vibrational modes. The calculations involve scaling of the force field in redundant internal coordinates as proposed by Pulay et al. The scaled quantum mechanical (SQM) calculations yield excellent agreement with experiment for the 14 allowed frequencies. This provides the basis for an accurate assignment of all nonallowed fundamentals and the reassignment of the observed overtone and combination bands of the high-resolution Raman (Wang et al., 1993) and IR (Martin et al. 1994) spectra. The calculated intensity ratios for the four IR active bands agree with experiment. The large IR intensity enhancements observed for C 60 6relative to C 60 are explained by the enhancement of certain components of the atomic polar tensor that is partially due to bond equalization in the charged fullerene. This enhancement appears to be largely a molecular rather then a solid state effect.

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Far-infrared study of C60-tetraphenylphosphoniumiodide

Cited by 5 publications

References 9 publications

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

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

Pressure-induced transition from the dynamic to static Jahn-Teller effect in (Ph4P)2IC60

Vibrational Assignment of All 46 Fundamentals of C₆₀ and C₆₀^6-: Scaled Quantum Mechanical Results Performed in Redundant Internal Coordinates and Compared to Experiments

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Far-infrared study of C60-tetraphenylphosphoniumiodide

Cited by 5 publications

References 9 publications

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

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

Pressure-induced transition from the dynamic to static Jahn-Teller effect in (Ph4P)2IC60

Vibrational Assignment of All 46 Fundamentals of C60 and C606-: Scaled Quantum Mechanical Results Performed in Redundant Internal Coordinates and Compared to Experiments

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Vibrational Assignment of All 46 Fundamentals of C₆₀ and C₆₀^6-: Scaled Quantum Mechanical Results Performed in Redundant Internal Coordinates and Compared to Experiments