Rotational Sublevels of an Ortho-Hydrogen Molecule Encapsulated in an Isotropic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="bold">C</mml:mi><mml:mn>60</mml:mn></mml:msub></mml:math>Cage

Kohama, Yoshimitsu; Rachi, Takeshi; Ju, Jing; Li, Zhaofei; Tang, Jun; Kumashiro, Ryotaro; Izumisawa, Satoru; Kawaji, Hitoshi; Ataké, Tooru; Sawa, Hiroshi; Murata, Yasujiro; Komatsu, Kôichi; Tanigaki, Katsumi

doi:10.1103/physrevlett.103.073001

Cited by 46 publications

(34 citation statements)

References 16 publications

(29 reference statements)

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“…If these effects are important their contribution to the IR spectra is of the order of one wavenumber splitting of a few absorption lines. Such small splitting is consistent with the NMR [28,29] and heat capacity [30] results. C 70 has an ellipsoidal shape and this splits the translation-rotation states of H 2 .…”

Section: Discussionsupporting

confidence: 90%

Infrared spectroscopy of small-molecule endofullerenes

Rõõm

Peedu

et al. 2013

Phil. Trans. R. Soc. A.

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Hydrogen is one of the few molecules that has been incarcerated in the molecular cage of C 60 to form the endohedral supramolecular complex H 2 @C 60 . In this confinement, hydrogen acquires new properties. Its translation motion, within the C 60 cavity, becomes quantized, is correlated with its rotation and breaks inversion symmetry that induces infrared (IR) activity of H 2 . We apply IR spectroscopy to study the dynamics of hydrogen isotopologues H 2 , D 2 and HD incarcerated in C 60 . The translation and rotation modes appear as side bands to the hydrogen vibration mode in the mid-IR part of the absorption spectrum. Because of the large mass difference of hydrogen and C 60 and the high symmetry of C 60 the problem is almost identical to a vibrating rotor moving in a three-dimensional spherical potential. We derive potential, rotation, vibration and dipole moment parameters from the analysis of the IR absorption spectra. Our results were used to derive the parameters of a pairwise additive five-dimensional potential energy surface for H 2 @C 60 . The same parameters were used to predict H 2 energies inside C 70 . We compare the predicted energies and the low-temperature IR absorption spectra of H 2 @C 70 .

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Section: Discussionsupporting

confidence: 90%

Infrared spectroscopy of small-molecule endofullerenes

Rõõm

Peedu

et al. 2013

Phil. Trans. R. Soc. A.

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“…(d) Rotational fine structure: the rotational peak studied at low temperature Using heat capacity measurements at low temperature, Kohama et al [29] have suggested there is evidence for a splitting of the order of 0.1-0.2 meV of the principal rotational peak centred on | E 0−1 | = 14.7 meV. The C 60 cage is icosahedral so the potential energy surface has too high a symmetry to be responsible for such a splitting.…”

Section: Results and Discussion (A) The Low Temperature Inelastic Neumentioning

confidence: 99%

Quantum rotation and translation of hydrogen molecules encapsulated inside C ₆₀ : temperature dependence of inelastic neutron scattering spectra

Horsewill

Goh

Rols

et al. 2013

Phil. Trans. R. Soc. A.

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The quantum dynamics of a hydrogen molecule encapsulated inside the cage of a C 60 fullerene molecule is investigated using inelastic neutron scattering (INS). The emphasis is on the temperature dependence of the INS spectra which were recorded using time-of-flight spectrometers. The hydrogen endofullerene system is highly quantum mechanical, exhibiting both translational and rotational quantization. The profound influence of the Pauli exclusion principle is revealed through nuclear spin isomerism. INS is shown to be exceptionally able to drive transitions between ortho -hydrogen and para -hydrogen which are spin-forbidden to photon spectroscopies. Spectra in the temperature range 1.6≤ T ≤280 K are presented, and examples are given which demonstrate how the temperature dependence of the INS peak amplitudes can provide an effective tool for assigning the transitions. It is also shown in a preliminary investigation how the temperature dependence may conceivably be used to probe crystal field effects and inter-fullerene interactions.

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“…Such small splitting is consistent with the results of heat capacity measurements. 43 We do not explain how the determined parameters are linked to the molecular structure of the H 2 @C 60 complex. In principle it should be possible to describe, within a single quantum chemical model of H 2 @C 60 , the potential parameters, induced dipole parameters, the dependence of both on the vibrational state, and the changes of rotational and vibrational constants compared to free H 2 values.…”

Section: Discussionmentioning

confidence: 99%

Interaction potential and infrared absorption of endohedral H2 in C60

Nagel

Hüvonen

et al. 2011

The Journal of Chemical Physics

109

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We have measured the temperature dependence of the infrared spectra of a hydrogen molecule trapped inside a C 60 cage, H 2 @C 60 , in the temperature range from 6 to 300 K and analyzed the excitation spectrum by using a five-dimensional model of a vibrating rotor in a spherical potential. The electric dipole moment is induced by the translational motion of endohedral H 2 and gives rise to an infrared absorption process where one translational quantum is created or annihilated, N = ±1. Some fundamental transitions, N = 0, are observed as well. The rotation of endohedral H 2 is unhindered but coupled to the translational motion. The isotropic and translation-rotation coupling part of the potential are anharmonic and different in the ground and excited vibrational states of H 2 . The vibrational frequency and the rotational constant of endohedral H 2 are smaller than those of H 2 in the gas phase. The assignment of lines to ortho-and para-H 2 is confirmed by measuring spectra of a para enriched sample of H 2 @C 60 and is consistent with the earlier interpretation of the low temperature infrared spectra [Mamone et al., J. Chem. Phys. 130, 081103 (2009)].

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Rotational Sublevels of an Ortho-Hydrogen Molecule Encapsulated in an IsotropicC60Cage

Cited by 46 publications

References 16 publications

Infrared spectroscopy of small-molecule endofullerenes

Infrared spectroscopy of small-molecule endofullerenes

Quantum rotation and translation of hydrogen molecules encapsulated inside C ₆₀ : temperature dependence of inelastic neutron scattering spectra

Interaction potential and infrared absorption of endohedral H2 in C60

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Rotational Sublevels of an Ortho-Hydrogen Molecule Encapsulated in an IsotropicC60Cage

Cited by 46 publications

References 16 publications

Infrared spectroscopy of small-molecule endofullerenes

Infrared spectroscopy of small-molecule endofullerenes

Quantum rotation and translation of hydrogen molecules encapsulated inside C 60 : temperature dependence of inelastic neutron scattering spectra

Interaction potential and infrared absorption of endohedral H2 in C60

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Product

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Quantum rotation and translation of hydrogen molecules encapsulated inside C ₆₀ : temperature dependence of inelastic neutron scattering spectra