TP14



Code: TP14 Time Slot/Poster Number: 149 Session: Sum Frequency Generation/Combined IR-Raman

Terahertz and FT-IR Spectral Analysis of a NLO material L-Glutamine Picrate: A DFT Study
M.Amala Nathan; I. Hubert Joe
University of Kerala, Trivandrum, India

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Summary
Terahertz time-domain spectroscopy was used to measure the absorption spectra of L-Glutamine Picrate . A number of absorption peaks were observed in THz region , which are interpreted as originating from inter- and intramolecular vibrational modes. In parallel with the experimental study, density functional theory was applied to obtain structure and vibrational wavenumbers of the isolated L-glutamine picrate .

Code: TP14 Time Slot/Poster Number: 150 Session: Sum Frequency Generation/Combined IR-Raman

FT-Raman and IR Spectral Analysis and DFT Computations of NLO Crystal L-Valine Hydrobromide
I. Hubert Joe
University of Kerala, Trivandrum, India

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Summary
Vibrational spectral analysis of the non linear optical crystal L-Valine Hydrobromide have been analyzed using NIR-FT Raman and FT-IR spectroscopy. The density functional theory computation have been performed at B3LYP/6-31G(d) level. The charge transfer interaction between the bromine ion and the NH3+ through ionic hydrogen bonding is confirmed by NBO analysis. The HOMO and LUMO energies and first hyperpolarizability are calculated.

Code: TP14 Time Slot/Poster Number: 151 Session: Sum Frequency Generation/Combined IR-Raman

Structural Conformation and Vibrational studies of Nonlinear Optical material L-Prolinium picrate
I. Hubert Joe1; V.K. Rastogi2; Bismi Edwin 1
1University of Kerala, Trivandrum, India; 2Department of Physics, CCS University, MEERUT, INDIA

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Summary
Vibrational spectral analysis and quantum chemical computations based on density functional theory have been performed on the nonlinear optical crystal L-prolinium picrate. The optimized geometry and harmonic vibrational frequencies of the compound have been investigated. The thermodynamic properties of the two conformers obtained by the variation in the location of the hydrogen atom in the carboxyl group are compared and the one which is more stable is chosen for vibrational analysis. A reliable assignment of the fundamentals was proposed based on the calculated wavenumber values and experimental infrared and Raman spectra. The first order hyperpolarizability of LPP was also calculated.

Code: TP14 Time Slot/Poster Number: 152 Session: Sum Frequency Generation/Combined IR-Raman

VIBRATIONAL STUDIES OF THE NONLINEAR OPTICAL CRYSTAL – 2,4-DINITROPHENOL
Varadharajan Krishnakumar
Periyar University, Salem,Tamilnadu, India

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Summary
Organic single crystals are promising materials for non linear optical applications. 2,4 dinitro phenol is an organic crystal grown by slow evaporation solution growth technique. The crystals were studied by applying Raman spectroscopy. Polarised Raman spectra were recorded at different geometries and the significance of the spectra were discussed in detail. Besides Hyperpolarizibility calculations were calculated using HF 3-21 G level and the importance of the results were also discussed.

Code: TP14 Time Slot/Poster Number: 153 Session: Sum Frequency Generation/Combined IR-Raman

Orientation of Polycyclic Aromatic Hydrocarbon molecules in Langmuir-Blodgett films using Sum Frequency Generation spectroscopy
A. Ballard Andrews1; Arthur McClelland2; Oona Korkeila1; Amber Krummel3; Alex Demidov2; Zhan Chen4
1Schlumberger Doll Research, Cambridge, MA; 2Northeastern University, Boston, MA; 3Harvard University, Cambridge, MA; 4University of Michigan, Ann Arbor, MI

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Summary
While many phenomenological interfacial studies with Polycyclic Aromatic Hydrocarbons have been reported little is known at the molecular level. PAHs are among the surface active constituents (e.g. asphaltenes) found in crude oils, so improved understanding of their interfacial properties could eventually lead to increases in produced crude oil by enhanced oil recovery methods. Our results demonstrate that the inherent complexity of the asphaltene crude oil sub-fraction is not a barrier to investigating interfacial properties at molecular scale. If nano-aggregates form during the compression phase prior to deposition, our results suggest that they retain a molecular orientation memory.