Analysis of vibrational spectra in relation to the thermodynamic quantities close to the phase transitions in ammonium halides (NH4F and NH4I)

Date

2017-01-01

Author

Tari, O.
Yurtseven, Hasan Hamit

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

88
views

0
downloads

The pressure dependences of the vibrational frequencies of the TO and L modes are analyzed from the literature data and the thermodynamic quantities such as isothermal compressibility K gamma, thermal expansion alpha p and the specific heat C-p - C-v are calculated through the mode Grilneisen parameters of those modes in ammonium halides (NH4F and NH4I). For this calculation, the observed frequencies of the TO mode (238 cm(-1) at 1 bar) and the L mode (74.7 meV at 1.9 GPa) are used for the phases of I, II and III in NH4F, whereas for the phases of V and VI in NH4F, the observed frequencies of the 238 cm(-1) are used as a function of pressure at T=293 K. We also analyze the observed frequencies for the TO (17.1 meV) and L (34.1 meV) modes (P=0, T=-25 degrees C) in the phase II of NH4I and the thermodynamic quantities (K-T, alpha(p) and C-p - C-v) are calculated as a function of pressure (T=-25 degrees C) through the mode Gruneisen parameters of the TO and L modes in phase II of NH(4)l.

Subject Keywords

NH4F and NH4I, Thermodynamic quantities, TO and L modes, Vibrational spectra

URI

https://hdl.handle.net/11511/41972

Journal

OPTIK

DOI

https://doi.org/10.1016/j.ijleo.2017.01.107

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

Calculation of the thermodynamic quantities from the Raman frequency shifts and the Pippard relations for the alpha, -alpha and alpha ' phases of oxygen Tari, O.; Yurtseven, Hasan Hamit (2018-01-01) Thermodynamic quantities such as the isothermal compressibility, thermal expansion and the difference in the specific heat are calculated as a function of pressure (T=10 K) for the alpha,-alpha and alpha ' phases of oxygen using the observed Raman frequencies of the two librons and one vibron from the literature through the mode Gruneisen parameter for this molecular solid. Calculated thermodynamic quantities decrease with increasing pressure with some discrepancies due to the different pressure - induced R...
Analysis of the Raman Frequency Shifts for the Lattice Modes and Vibrons Related to the Thermodynamic Quantities in the eta Phase of Solid Nitrogen Yurtseven, Hasan Hamit (Walter de Gruyter GmbH, 2013-08-01) The thermodynamic quantities of the isothermal compressibility, thermal expansion and the specific heat are calculated here as a function of pressure by using the observed Raman frequencies of the lattice modes and vibrons in the. phase of solid nitrogen. The Pippard relations and their spectroscopic modifications are constructed, and the slope dP/dT is deduced from the Raman frequency shifts in this phase of N-2. It is shown that the thermodynamic quantities can be predicted from the Raman frequency shifts...
Analysis of the Raman intensities near the phase transitions in ammonium halides Yurtseven, Hasan Hamit (Elsevier BV, 2008-12-01) This study concentrates on the temperature dependence of the Raman intensities for the lattice modes in ammonium halides (NH4Cl and NH4Br) close to phase transitions, We predict their intensities using the results of a shell model for the Raman polarizability within the framework of an Ising pseudospin-phonon coupled model.
Analysis of the Raman frequency as an order parameter close to the melting point in biphenyl Yurtseven, Hasan Hamit (2017-05-01) We analyze the observed Raman frequencies of the three lattice modes (modes A, B and 70cm-1) near the melting point in biphenyl by calculating the temperature dependence of the order parameter from the mean field theory. This is based on the correlation between the frequency and the order parameter close to the melting temperature (Tm=343K) in biphenyl. The Raman frequencies of the modes A and B decrease rapidly as the melting temperature is approached, whereas the Raman frequency of the 70 cm-1 is smoothly...
Calculation of the Raman frequency as a function of pressure for the phases of I, III, IV and V in cyclohexane Yurtseven, Hasan Hamit (2014-06-05) The Raman frequencies of the v(5) mode are calculated as a function of pressure up to 10 GPa (room temperature) for the phases I, III, IV and V of cyclohexane using the volume data from the literature by means of the isothermal mode Griineisen parameter gamma(T) of this mode.

Citation Formats

O. Tari and H. H. Yurtseven, “Analysis of vibrational spectra in relation to the thermodynamic quantities close to the phase transitions in ammonium halides (NH4F and NH4I),” OPTIK, pp. 244–251, 2017, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41972.