Ordering phenomena in C

Launois, Pascale; Moret, R.; Souza, Nicolas R. de; Azamar-Barrios, J.A.; Pénicaud, A.

doi:10.1007/s100510051145

Cited by 8 publications

(12 citation statements)

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“…The rapid modulations of the molecular form factor ͑large size of C 60 ͒ give rise to pronounced modulations of the halo. Similar results are obtained in the case of fullerene-biphenyl and of fullerene-tetraphenylphosphonium bromide compounds, 28,29 where different molecular orientations are also present. To try to explain the observed diffuse scattering in the lowtemperature phase of fullerene-cubane, we have calculated the diffuse scattering for 24 different orientations of the C 60 molecules.…”

Section: A Diffuse Scatteringsupporting

confidence: 83%

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

et al. 2010

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The dynamics of fullerene-cubane ͑C 60 ·C 8 H 8 ͒ cocrystal is studied combining experimental ͓x-ray diffuse scattering, quasielastic and inelastic neutron scattering ͑INS͔͒ and simulation ͑molecular dynamics͒ investigations. Neutron scattering gives direct evidence of the free rotation of fullerenes and of the libration of cubanes in the high-temperature phase, validating the "rotor-stator" description of this molecular system. X-ray diffuse scattering shows that orientational disorder survives the order/disorder transition in the low-temperature phase, although the loss of fullerene isotropic rotational diffusion is featured by the appearance of a 2.2 meV mode in the INS spectra. The coupling between INS and simulations allows identifying a degeneracy lift of the cubane librations in the low temperature phase, which is used as a tool for probing the environment of cubane in this phase and for getting further insights into the phase transition mechanism.

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Section: A Diffuse Scatteringsupporting

confidence: 83%

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

et al. 2010

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“…38 Since the fourfold crystallographic symmetry is not replicated in the I h point group, 39 there are two equivalent perpendicular orientations of the C 60 − cage that are randomly occupied. 34,36,37 Although both the disorder and the JT effect are reported to be static at low temperature, 36,40,41 no distortion of C 60 − in ͑Ph 4 X͒ 2 YC 60 has been detected by x-ray diffraction [34][35][36][37] or diffuse x-ray scattering, 42 and an upper bound of 0.01 Å has been set on deviations from an I h symmetry cage. 36 In addition to the structural studies, other experimental methods have been employed to clarify the properties of the C 60 monoanion in the ͑Ph 4 X͒ 2 YC 60 set of materials.…”

Section: Introductionmentioning

confidence: 99%

“…36 In addition to the structural studies, other experimental methods have been employed to clarify the properties of the C 60 monoanion in the ͑Ph 4 X͒ 2 YC 60 set of materials. 33,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] Of particular relevance for this paper is a previous vibrational study of ͑Ph 4 P͒ 2 IC 60 which found splitting of the T 1u C 60 modes and activation of silent vibrations, consistent with a D 5d or D 3d JT distortion of the cage. 55 Although a JT distortion of C 60 − was successfully confirmed, the accuracy of the symmetry identification was limited because a strong counterion vibration obscures the region of the fundamental T 1u ͑1͒ vibration and because no comparison was made to a calculated spectrum.…”

Section: Introductionmentioning

confidence: 99%

Jahn-Teller distortion ofC60−in(Ph4As)2
Long
¹
,
Schundler
²
,
Adams
³

et al. 2007
Phys. Rev. B
9
1
20
0
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We report a combined experimental and theoretical study of the on-ball vibrations of the singly charged C 60 anion. The experimental material is ͑Ph 4 As͒ 2 ClC 60 , a prototypical system for studying isolated C 60 − , which we have investigated by high-resolution infrared spectroscopy in the range 50-1500 cm −1 between 6 and 300 K. Our first-principles quantum molecular dynamics calculations provide complementary information on the vibrational spectra as well as simulated structural information about the reduced-symmetry cage. Our combined results indicate either C 2h or C i symmetry for the Jahn-Teller distorted cage. In both cases, the cage is prolate and elongated along an axis that penetrates opposing five-membered rings. Bond-length changes are less than 0.013 Å. Observed temperature-dependent frequency shifts of the C 60 − vibrations are insufficient to identify any ordering transition, although low-temperature softening of a T 1u ͑4͒-derived mode is substantial.

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“…4. Previous studies on C 60 and related compounds have revealed the signature of an ordering transition induced by pressure and temperature [14,15,18]. The nature of this transition has been found more complicated than simple orientational ordering [18].…”

Section: High Pressurementioning

confidence: 99%

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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Ordering phenomena in C

Cited by 8 publications

References 0 publications

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

Jahn-Teller distortion ofC60−in(Ph4As)2
Long
¹
,
Schundler
²
,
Adams
³

et al. 2007
Phys. Rev. B
9
1
20
0
View full text Add to dashboard Cite

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

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Ordering phenomena in C

Cited by 8 publications

References 0 publications

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubaneC60⋅C8H8

Jahn-Teller distortion ofC60−in(Ph4As)2Long1, Schundler2, Adams3 et al. 2007Phys. Rev. B91200View full textAdd to dashboardCite

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

Contact Info

Product

Resources

About

Jahn-Teller distortion ofC60−in(Ph4As)2
Long
¹
,
Schundler
²
,
Adams
³

et al. 2007
Phys. Rev. B
9
1
20
0
View full text Add to dashboard Cite