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Bagatskii, M. I.; Manzheliı̆, V. G.; Minchina, I. Ya.; Mashchenko, D. A.; Gospodarev, I. A.

doi:10.1023/a:1022463618264

Cited by 11 publications

(20 citation statements)

References 22 publications

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“…The conversion of molecules deuteromethane has been first found in the solid solutions (CD 4 ) x Kr. 35,36 The behavior of the experimental temperature dependences s CH4 (T) and s CD4 (T), 13 as in cases of solid solutions (CH 4 ) x Kr, 32,33 (CD 4 ) x Kr, 35,36 agrees qualitatively with the theoretical data on conversion in multiatomic molecules. In contrast to diatomic molecules, [37][38][39][40] other mechanisms of conversion are dominant in multiatomic molecules at low temperatures.…”

Section: Resultssupporting

confidence: 75%

“…32,33 The low-energy parts of the rotational spectra of the A-, T-and E-species of CH 4 are as for CD 4 dependent on the symmetry and value of the crystal field. The rotators CH 4 and CD 4 are therefore an effective probe of the crystal environment in the octahedral cavities of the fullerite C 60 .…”

Section: Resultsmentioning

confidence: 99%

“…At s CH4 $ t m the heat capacity C CH4 (T) depends on the number of CH 4 molecules which convert during the time t m . 32 The characteristic time s CH4 (T) of the conversion in CH 4 molecules can be described as…”

Section: Resultsmentioning

confidence: 99%

“…In our experiment s CH4 % t m and C CH4 (T) is determined by the number of CH 4 molecules which converted during the effective time t m of a single heat capacity measurement. 32 Above 8 K C CH4 (T) corresponds to the equilibrium distribution of CH 4 species. The relatively fast drop of the theoretical C rot,eq (T) values in the region T ¼ 8-12 K suggests that the higher-lying energy levels of the molecules CH 4 (than for those shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In the regions T ¼ 1.3-5.5 K and T ¼ 1.4-8 K the experimental heat capacities C CD4 (T) and C CH4 (T) are dependent on the number of the molecules which converted during the effective time t m of a single run of heat capacity measurement. 32 The heat capacities C CD4 (T) above %5.5 K and C CH4 (T) above %8 K correspond to the equilibrium distribution of the molecular species.…”

Section: Resultsmentioning

confidence: 99%

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Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Bagatskii

Manzheliı̆

Sumarokov

et al. 2014

Low Temperature Physics

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The heat capacity of the interstitial solid solution (CH 4 ) 0.4 C 60 has been investigated in the temperature interval 1.4-120 K. The contribution of CH 4 molecules to the heat capacity of the solution has been separated. The contributions of CH 4 and CD 4 molecules to the heat capacity of the solutions (CH 4 ) 0.40 C 60 and (CD 4 ) 0.40 C 60 have been compared. It is found that above 90 K the character of the rotational motion of CH 4 and CD 4 molecules changes from libration to hindered rotation. In the interval 14-35 K the heat capacities of CH 4 and CD 4 molecules are satisfactorily described by contributions of the translational and libration vibrations, as well as the tunnel rotation for the equilibrium distribution of the nuclear spin species. The isotope effect is due to mainly, the difference in the frequencies of local translational and libration vibrations of molecules CH 4 and CD 4 . The contribution of the tunnel rotation of the CH 4 and CD 4 molecules to the heat capacity is dominant below 8 K. The isotopic effect is caused by the difference between both the conversion rates and the rotational spectra of the nuclear spin species of CH 4 and CD 4 molecules. The conversion rate of CH 4 molecules is several times lower than that of CD 4 ones. Weak features observed in the curves of temperature dependencies of the heat capacity of CH 4 and CD 4 molecules near 6 and 8 K, respectively, are most likely a manifestation of first-order polyamorphic phase transitions in the orientational glasses of these solutions. V C 2014 AIP Publishing LLC. [http://dx

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Bagatskii

Manzheliı̆

Sumarokov

et al. 2014

Low Temperature Physics

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Phonon scattering by quantum rotor and spin conversion in solid Kr‐CH ₄ solutions

Кривчиков¹,

Gorodilov

Korolyuk

et al. 2004

phys. stat. sol. (c)

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The measurement results on the thermal conductivity K(T) of solid Kr 1-x (CH 4 ) x solutions in the interval 2-40 K, x = 0-1, are reported. The temperature dependences K(T) taken in the solutions in concentrated orientationally-ordered and orientationally-disordered phases have features that are not typical of dielectric crystals. It is shown that the anomalous K(T) is caused by strong single-phonon resonance scattering at a weakly hindered quantum rotor-the CH 4 molecule with the nuclear spin I = 1.1 Introduction. A molecule freely rotating in a crystal does not interact with its surroundings. In actual practice, however, when certain properties of condensed phases containing rotating molecules (rotors) are considered, it is important to take into account even weak noncentral interactions of these molecules with the surrounding particles. The rotor-lattice interaction in a crystalline system is called a phonon-rotation interaction (PRI) [1]. Precisely PRI brings the translational vibrations of the lattice and the rotation of the molecules to equilibrium. PRI can in particular affect the thermal conductivity of the substance [2][3][4]. In the crystalline state the character of molecular rotation is dependent not only on the force of interparticle interactions but on the thermal vibrations of the lattice as well.In the solid Kr 1-x (CH 4 ) x solution we can observe quantum-mechanical rotation at low temperatures and rotational diffusion of the molecules at high temperatures. Owing to the spherical symmetry of Kr atoms and the close Lennard-Jones potential of methane and krypton, the rotation of CH 4 molecules is weakly hindered, no considerable stress are induced in the lattice of solid solution and its components are characterized by high mutual solubility in the solid phase.This investigation of thermal conductivity was made on a two-component crystal system of weakly hindered rotors and inert gas atoms whose parameters of the Lennard-Jones potential were close to those of the rotors.The goal of this work was to investigate the influence of PRI on the thermal conductivity of solid CH 4 -Kr solutions in which the CH 4 subsystem is viewed as an ensemble of rotors interacting with one to another and with the translational vibrations of the lattice. Varying the CH 4 concentration in the solution, it is possible to trace how the PRI changes on transition from the system with a weak noncentral interaction to the system with a party orientational order in orientationally-ordered phase II of methane. Three fourths of the CH 4 molecules perform heavily hindered rotational motion (small-angle orientational vibrations-librations) in a strong anisotropic molecular field of D 2d symmetry; one fourth of the molecules (rotors) rotate almost freely in the crystal field having the octahedral symmetry O h . Each of these types of rotational excitations scatters the phonons and contributes to the thermal resistance. It is found [5],

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Low Temperature Anomaly of Heat Capacity of CD4 Rotors in Solid CD4–Kr Solution

et al. 2005

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Untitled

Cited by 11 publications

References 22 publications

Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Phonon scattering by quantum rotor and spin conversion in solid Kr‐CH ₄ solutions

Low Temperature Anomaly of Heat Capacity of CD4 Rotors in Solid CD4–Kr Solution

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Untitled

Cited by 11 publications

References 22 publications

Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

Phonon scattering by quantum rotor and spin conversion in solid Kr‐CH 4 solutions

Low Temperature Anomaly of Heat Capacity of CD4 Rotors in Solid CD4–Kr Solution

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Phonon scattering by quantum rotor and spin conversion in solid Kr‐CH ₄ solutions