Relaxation Time of Concentration Fluctuations in a Vicinity of the Critical Stratification Point of the Binary Mixture n-Pentanol–Nitromethane


  • L. A. Bulavin Taras Shevchenko National University of Kyiv, Institute for Safety Problems of Nuclear Power Plants, Nat. Acad. of Sci. of Ukraine
  • O. I. Bilous Taras Shevchenko National University of Kyiv
  • O. S. Svechnikova Taras Shevchenko National University of Kyiv



ultrasound velocity, ultrasound absorption, critical stratification point, binary solution, concentration fluctuations, relaxation time


The propagation velocity and the absorption coefficient of ultrasound in a frequency range of 5–2800 MHz in a n-pentanol–nitromethane solution in a vicinity of its critical stratification point from the homogeneous state side have been studied. The research make it possible to reveal the influence of concentration fluctuations on the sound propagation velocity. Three regions of dynamical parameters are analyzed: the mean-field (wтFL ≪ 1), fluctuation (wтFL ≫ 1), and transition (crossover, wтFL = 1) ones. On the basis of experimental data, the temperature dependence of the concentration fluctuation relaxation time т(T) is studied, and its magnitude т0 is determined. The contribution to the fluctuation part of the sound absorption coefficient at high frequencies (w > 300 MHz), which is connected with the sound scattering by concentration fluctuations near the critical stratification point is estimated.


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How to Cite

Bulavin, L. A., Bilous, O. I., & Svechnikova, O. S. (2019). Relaxation Time of Concentration Fluctuations in a Vicinity of the Critical Stratification Point of the Binary Mixture n-Pentanol–Nitromethane. Ukrainian Journal of Physics, 61(10), 879.



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