V Ramakrishnan
Articles written in Pramana – Journal of Physics
Volume 30 Issue 2 February 1988 pp 129-133 Molecular Physics
Infrared and Raman spectra of aquamolybdenum (VI) oxide hydrate (MoO3·2H2O)
Daizy Philip G Aruldhas V Ramakrishnan
The infrared and Raman spectra of MoO3·2H2O are recorded and analysed on the basis of vibrations due to MoO6 octahedra and H2O molecules. Considerable changes in the frequencies of the octahedra have been observed due to strong distortion in the octahedral arrangement. The inactive
Volume 33 Issue 6 December 1989 pp 659-665 Spectroscopy
Infrared and raman studies on neodymium pentaphosphate and metaphosphates
V Ramakrishnan J Kumar M Thirumavalavan F D Gnanam P Ramasamy
The infrared and Raman spectra of crystalline samples of NdP5O14, NaNdP4O12 and KNdP4O12 are recorded. The spectra are analysed on the basis of vibrations of P=O, P-O, PO2 and P-O-P groups. The P4O124− ion has cyclic structures both in NaNdP4O12 and KNdP4O12 crystals. It has been inferred that the P-O-P bridges are stronger in metaphosphates.
Volume 34 Issue 6 June 1990 pp 555-560
Vibrational spectra of Na4P2O7·10H2O
V Ramakrishnan S Narayana Kalkura P Rajagopal
The IR and Raman spectra are measured and analysed for sodium pyrophosphate decahydrate. The spectra are interpreted on the basis of P2O74− ion and water vibrations. The observed results fit with the features predicted for the factor goup model. The appearance of two sets of frequencies in the stretching and bending regions of water suggests the existence of two kinds of water molecules in the crystal. This is confirmed by deuterium substitution.
Volume 36 Issue 6 June 1991 pp 603-610
Vibrational spectra of (NH4)3ZnCl5
M Balasubramanian V Ramakrishnan S Rajendran
IR and Raman spectra of (NH4)3ZnCl5 have been recorded. The observed spectra have been analysed on the basis of the vibrations of ZnCl42− and NH4+ ions. The appearance of multiple Raman bands indicates the presence of two different types of ammonium ions. The effect of anisotropic crystalline field over the ZnCl4 and NH4 tetrahedra is also discussed. The assignment of internal modes has been verified by the potential energy distribution calculations.
Volume 39 Issue 6 December 1992 pp 633-637
SERS studies of 1-butylaminoanthraquinone in silver sol
V Ramakrishnan A Narayana Perumal N Krishnamurthy V J P Srivatsavoy
SERS studies of 1-butylaminoanthraquinone in silver sol have been made to understand the nature of adsorption. The enhancement mechanism is explained on the basis of charge transfer process. The molecule is adsorbed through the binding sites but not flat on to the surface.
Volume 41 Issue 5 November 1993 pp 467-472 Research Articles
SERS studies on 1–4 dihydroxyanthraquinone at Ag electrode
V G Srikanth S Edwin Jayaraj V Ramakrishnan
Raman scattering studies on 1–4 dihydroxyanthraquinone (DHAQ) at Ag electrode have been carried out to investigate the enhancement in the spectral line intensity after adsorption. Charge transfer between the adsorbate and the substrate is more pronounced for certain normal modes of vibration. It is found that the DHAQ molecules are lying with their molecular plane on the top of the metal surface. Laser induced fluorescence spectra of DHAQ have also been analysed with a view to assign the relative orientation of absorption and emission dipoles.
Volume 47 Issue 3 September 1996 pp 255-259
Surface enhanced Raman scattering studies of acetophenone on colloidal silver particles
S Edwin Jayaraj V Ramakrishnan S Perumal M Gurunathan
Intense Raman scattering by acetophenone molecules adsorbed on colloidal silver particles is reported. Greater enhancement is observed for the ring breathing and ring stretching vibrations. The orientation determination analysis shows that the adsorption of acetophenone molecule is neither through its co-ordinating site nor through its
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