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Showing papers by "Ranjan K. Singh published in 2009"


Journal ArticleDOI
TL;DR: In this article, the solid to smecticG (SmG) phase transition in a Schiff base liquid crystalline compound, terepthal-bis-heptylaniline (TB7A), is monitored in situ by temperature-dependent Raman microspectroscopy, using the band of a CH inplane bending mode as a marker.
Abstract: The solid to smecticG (SmG) phase transition in a Schiff base liquid crystalline compound, terepthal-bis-heptylaniline (TB7A), is monitored in situ by temperature-dependent Raman microspectroscopy, using the band of a CH in-plane bending mode as a marker. Contrary to the earlier report of a sudden wavenumber shift, the in situ measurement shows very clearly that a new Raman band at ∼1160 cm−1 appears at the Crystal II SmG transition. The dynamics of this phase transition is discussed in terms of a triple well potential below 210 K and a double well potential above 210 K. The phase transition essentially takes place as a result of intra-molecular rotation about the long molecular axis. The optimization energy at various fixed dihedral angles, (CCCN) are calculated using density functional theory (DFT) at the B3LYP/6-31G* level of theory. The relative energy at each dihedral angle is calculated relative to optimization energy obtained without any constraints and plotted as a function of dihedral angle (Φ) between the adjacent phenyl ring planes, which also shows a double well potential at room temperature. Copyright © 2009 John Wiley & Sons, Ltd.

21 citations


Journal ArticleDOI
07 Jan 2009
TL;DR: In this article, the binding interactions between the benzonitrile and one/two silver atom complexes, [Bz+−1(2)Ag]0 and [bz++ 1/2Ag]+1 have been investigated using DFT calculations at B3LYP level employing three basis sets, Lanl2DZ, SDD and CEP-31G.
Abstract: The Raman spectra of benzonitrile (Bz) in silver colloidal solution have been recorded at different millimolar concentrations of benzonitrile in the spectral range, 400–2300 cm−1 and the spectral parameters of prominent bands in the region are discussed as a function of concentration. The binding interactions between the benzonitrile and one/two silver atom complexes, [Bz + 1(2)Ag]0 and [Bz + 1(2)Ag]+1 have been investigated using DFT calculations at B3LYP level employing three basis sets, Lanl2DZ, SDD and CEP-31G. The Bz molecule seems to be adsorbed in end-on orientation. The binding energy of [Bz + 2Ag]0 complex is greater than that of [Bz + 1Ag]0 complex. Some bands of benzonitrile show red shift upon surface coordination while some are blue shifted. The red shift in ν(C N) vibrational mode is discussed in terms of shortening of C–CN bond due to metal–adsorbate back donation.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the static and dynamic properties of pyridazine (PRD) in H2O (W) and D2O(D) environment were investigated using a polarized Raman and density functional theory approach.

5 citations