Dynamics of molecules and phase transitions in the crystals of pure and binary mixtures of n-paraffins

G. O. Puchkovska, S. P. Makarenko, V. D. Danchuk, A. P. Kravchuk, J. Baran, E. N. Kotelnikova, S. K. Filatov

Результат исследований: Научные публикации в периодических изданияхстатьянаучнаярецензирование

7 Цитирования (Scopus)

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In the present paper, we report on temperature dependent FR-IR spectra studies of the value of Davydov splitting for CH2 rocking vibrations of pure crystalline n-paraffins CnH2n+2 (with odd number n of carbon atoms) and some isomorphic substituted binary mixtures of n-paraffins C22/C24. It was shown that the temperature dependencies of Davydov splitting value are characterized by the number of irregularities (sharp decreasing), which correspond to phase transitions into the high-temperature (hexagonal) state for pure n-paraffins or different rotator crystalline states for the mixtures. A statistic and dynamic model is proposed which provides adequate description of the observed effect. In the framework of this model, two different mechanisms are responsible for the temperature behavior of the splitting value of vibrational modes. In addition to thermal expansion of crystals under heating, the damping of vibrational excitons on orientational defects of different nature takes place breaking the translational symmetry of the crystal lattice. Genesis of such defects is connected with excitation of librational and molecular rotational degrees of freedom at the crystal polymorphic transitions into different rotator crystalline states. Theoretical analysis of the effect of resonance dynamical intermolecular interaction on the spectra of intramolecular vibrations of the crystals was performed in terms of stochastic equations with account for mentioned phase transitions. Computer simulation of such dependence was performed for pure n-paraffin compounds. Good agreement between the experimental and computer simulation results was obtained.

Языканглийский
Страницы159-166
Число страниц8
ЖурналJournal of Molecular Structure
Том614
Номер выпуска1-3
DOI
СостояниеОпубликовано - 2 сен 2002

Ключевые слова

    Предметные области Scopus

    • Структурная биология
    • Органическая химия
    • Физическая и теоретическая химия
    • Спектроскопия
    • Атомная и молекулярная физика и оптика

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    title = "Dynamics of molecules and phase transitions in the crystals of pure and binary mixtures of n-paraffins",
    abstract = "In the present paper, we report on temperature dependent FR-IR spectra studies of the value of Davydov splitting for CH2 rocking vibrations of pure crystalline n-paraffins CnH2n+2 (with odd number n of carbon atoms) and some isomorphic substituted binary mixtures of n-paraffins C22/C24. It was shown that the temperature dependencies of Davydov splitting value are characterized by the number of irregularities (sharp decreasing), which correspond to phase transitions into the high-temperature (hexagonal) state for pure n-paraffins or different rotator crystalline states for the mixtures. A statistic and dynamic model is proposed which provides adequate description of the observed effect. In the framework of this model, two different mechanisms are responsible for the temperature behavior of the splitting value of vibrational modes. In addition to thermal expansion of crystals under heating, the damping of vibrational excitons on orientational defects of different nature takes place breaking the translational symmetry of the crystal lattice. Genesis of such defects is connected with excitation of librational and molecular rotational degrees of freedom at the crystal polymorphic transitions into different rotator crystalline states. Theoretical analysis of the effect of resonance dynamical intermolecular interaction on the spectra of intramolecular vibrations of the crystals was performed in terms of stochastic equations with account for mentioned phase transitions. Computer simulation of such dependence was performed for pure n-paraffin compounds. Good agreement between the experimental and computer simulation results was obtained.",
    keywords = "Davydov splitting, IR spectra, n-Paraffin, Rotator crystal state",
    author = "Puchkovska, {G. O.} and Makarenko, {S. P.} and Danchuk, {V. D.} and Kravchuk, {A. P.} and J. Baran and Kotelnikova, {E. N.} and Filatov, {S. K.}",
    year = "2002",
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    Dynamics of molecules and phase transitions in the crystals of pure and binary mixtures of n-paraffins. / Puchkovska, G. O.; Makarenko, S. P.; Danchuk, V. D.; Kravchuk, A. P.; Baran, J.; Kotelnikova, E. N.; Filatov, S. K.

    В: Journal of Molecular Structure, Том 614, № 1-3, 02.09.2002, стр. 159-166.

    Результат исследований: Научные публикации в периодических изданияхстатьянаучнаярецензирование

    TY - JOUR

    T1 - Dynamics of molecules and phase transitions in the crystals of pure and binary mixtures of n-paraffins

    AU - Puchkovska, G. O.

    AU - Makarenko, S. P.

    AU - Danchuk, V. D.

    AU - Kravchuk, A. P.

    AU - Baran, J.

    AU - Kotelnikova, E. N.

    AU - Filatov, S. K.

    PY - 2002/9/2

    Y1 - 2002/9/2

    N2 - In the present paper, we report on temperature dependent FR-IR spectra studies of the value of Davydov splitting for CH2 rocking vibrations of pure crystalline n-paraffins CnH2n+2 (with odd number n of carbon atoms) and some isomorphic substituted binary mixtures of n-paraffins C22/C24. It was shown that the temperature dependencies of Davydov splitting value are characterized by the number of irregularities (sharp decreasing), which correspond to phase transitions into the high-temperature (hexagonal) state for pure n-paraffins or different rotator crystalline states for the mixtures. A statistic and dynamic model is proposed which provides adequate description of the observed effect. In the framework of this model, two different mechanisms are responsible for the temperature behavior of the splitting value of vibrational modes. In addition to thermal expansion of crystals under heating, the damping of vibrational excitons on orientational defects of different nature takes place breaking the translational symmetry of the crystal lattice. Genesis of such defects is connected with excitation of librational and molecular rotational degrees of freedom at the crystal polymorphic transitions into different rotator crystalline states. Theoretical analysis of the effect of resonance dynamical intermolecular interaction on the spectra of intramolecular vibrations of the crystals was performed in terms of stochastic equations with account for mentioned phase transitions. Computer simulation of such dependence was performed for pure n-paraffin compounds. Good agreement between the experimental and computer simulation results was obtained.

    AB - In the present paper, we report on temperature dependent FR-IR spectra studies of the value of Davydov splitting for CH2 rocking vibrations of pure crystalline n-paraffins CnH2n+2 (with odd number n of carbon atoms) and some isomorphic substituted binary mixtures of n-paraffins C22/C24. It was shown that the temperature dependencies of Davydov splitting value are characterized by the number of irregularities (sharp decreasing), which correspond to phase transitions into the high-temperature (hexagonal) state for pure n-paraffins or different rotator crystalline states for the mixtures. A statistic and dynamic model is proposed which provides adequate description of the observed effect. In the framework of this model, two different mechanisms are responsible for the temperature behavior of the splitting value of vibrational modes. In addition to thermal expansion of crystals under heating, the damping of vibrational excitons on orientational defects of different nature takes place breaking the translational symmetry of the crystal lattice. Genesis of such defects is connected with excitation of librational and molecular rotational degrees of freedom at the crystal polymorphic transitions into different rotator crystalline states. Theoretical analysis of the effect of resonance dynamical intermolecular interaction on the spectra of intramolecular vibrations of the crystals was performed in terms of stochastic equations with account for mentioned phase transitions. Computer simulation of such dependence was performed for pure n-paraffin compounds. Good agreement between the experimental and computer simulation results was obtained.

    KW - Davydov splitting

    KW - IR spectra

    KW - n-Paraffin

    KW - Rotator crystal state

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    U2 - 10.1016/S0022-2860(02)00237-5

    DO - 10.1016/S0022-2860(02)00237-5

    M3 - Article

    VL - 614

    SP - 159

    EP - 166

    JO - Journal of Molecular Structure

    T2 - Journal of Molecular Structure

    JF - Journal of Molecular Structure

    SN - 0022-2860

    IS - 1-3

    ER -