Terahertz spectroscopy of dicyanobenzenes: Anomalous absorption intensities and spectral calculations

Esentürk, Okan
Heilweil, E. J.
Terahertz absorption spectra of three isomeric structures of dicyanobenzene in chloroform solution and solid phase at 298 K are reported. These spectra exhibit enhanced absorption in low THz range compared to most organic systems because of strong coupling to phonon modes. Molecular vibrational spectral calculations show strong correlation with the experiment especially for solution spectra. All intramolecular modes were assigned and intermolecular modes identified. Out-of-plane intramolecular modes at low frequency exhibit similar to 75 cm(-1) blue shifts as the secondary CN group moves from the para to ortho position on the benzene ring, whereas almost no frequency shift occurs for low-frequency in-plane modes.


Critical behaviour of the thermodynamic quantities close to phase transitions in molecular crystals using raman data
Özdemir, Hilal; Yurtseven, Hasan Hamit; Department of Physics (2017)
In this thesis we investigate the pressure and temperature dependence of the Raman frequencies for diffirent modes of benzene at ambient conditions (P=0 GPa and T=300 K). By using the experimental data we calculated the volume and frequency as a function of pressure at constant temperature and as a function of temperature at constant pressure, thus isothermal and isobaric mode Grüneisen parameter has been inferred in the diffrent modes. Our calculations show that calculated Raman frequencies agree well with...
Dielectric Properties of Ethanol and Gasoline Mixtures by Terahertz Spectroscopy and an Effective Method for Determination of Ethanol Content of Gasoline
ARIK, Enis; Altan, Hakan; Esentürk, Okan (American Chemical Society (ACS), 2014-05-01)
Investigation of frequency dependent permittivity of mixture solutions provides information on the role of intermolecular interactions on relaxation processes of solvent and solute molecules. In this study the dielectric properties of ethanol/gasoline mixtures in the terahertz spectral region are investigated. Frequency dependent absorption coefficients, refractive indices, and complex permittivities of pure ethanol and gasoline, and their mixtures at varying ethanol volume percentages (v/v %) are reported....
Valence-shell electron energy-loss spectra of formic acid and acetic acid
Ari, T; Guven, MH (2000-01-01)
Gas phase optical absorption spectra of formic acid and acetic acid in the energy ranges 5.0-11.3 and 4.4-11.3 eV, respectively, have been previously recorded. It is generally agreed that of the four successive bands observed in the spectra of these compounds, the first corresponds to n --> pi* transition. However, various assignments have been proposed for the following three bands. In the present study, electron energy-loss spectra of formic acid and acetic acid vapours at 70 eV impact energy and 0 degree...
Raman frequencies calculated as functions of temperature and pressure using volume data for solid phase I of benzene
Yurtseven, Hasan Hamit (2017-01-01)
Raman frequencies of six lattice modes are calculated as a function of pressure using the volume data from the literature by means of the isothermal mode Gruneisen parameter (gamma(T)) for the solid phase I of benzene. We find that by determining the yr decreasing, the Raman frequencies calculated for the phonon modes increase with increasing pressure in this solid phase of benzene, which agree with the observed Raman data. We also predict the T-P phase diagram between the solid phases of I and I' by using ...
Critical behaviour of the Raman frequency shifts in the vicinity of the lambda-phase transition in NH4Br
Yurtseven, Hasan Hamit (2006-01-01)
This study gives the temperature dependence of the Raman frequencies for the lattice mode of upsilon(7) (TA) and the internal mode of upsilon(2) close to the X-phase transition (T-lambda=234K, P=\) in NB4Br.
Citation Formats
O. Esentürk and E. J. Heilweil, “Terahertz spectroscopy of dicyanobenzenes: Anomalous absorption intensities and spectral calculations,” CHEMICAL PHYSICS LETTERS, pp. 71–77, 2007, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/45852.