K Safakath

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Publications (4)9.24 Total impact

  • Source
    Article: Ultrafast optical nonlinearity, electronic absorption, vibrational spectra and solvent effect studies of ninhydrin.
    D Sajan, T Uma Devi, K Safakath, Reji Philip, Ivan Němec, M Karabacak
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    ABSTRACT: FT-IR, FT-Raman and UV-Vis spectra of the nonlinear optical molecule ninhydrin have been recorded and analyzed. The equilibrium geometry, bonding features, and harmonic vibrational wavenumbers have been investigated with the help of B3LYP density functional theory method. A detailed interpretation of the vibrational spectra is carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. Solvent effects have been calculated using time-dependent density functional theory in combination with the polarized continuum model. Natural bond orbital analysis confirms the occurrence of strong intermolecular hydrogen bonding in the molecule. Employing the open-aperture z-scan technique, nonlinear optical absorption of the sample has been studied in the ultrafast and short-pulse excitation regimes, using 100fs and 5ns laser pulses respectively. It is found that ninhydrin exhibits optical limiting for both excitations, indicating potential photonic applications.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 03/2013; 109C:331-343. · 2.10 Impact Factor
  • Source
    Article: Multi-photon absorption effect and intra-molecular charge transfer of donor-π-acceptor chromophore ethyl p-amino benzoate.
    D Sajan, N Vijayan, K Safakath, Reji Philip, M Karabacak
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    ABSTRACT: Fourier transform (FT)-Raman and infrared (IR) spectra of the nonlinear optical (NLO) material ethyl p-amino benzoate (EPAB) have been recorded and analyzed. The geometry and harmonic vibrational wavenumbers are calculated with the help of B3LYP density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. Stability of the molecule arising from hyperconjugative interactions leading to its NLO activity and charge delocalization have been analyzed using natural bond orbital (NBO) analysis. Employing the open-aperture z-scan technique, NLO absorption of the sample has been studied in two excitation regimes, using 100fs and 5ns laser pulses respectively. It is found that EPAB is a three-photon absorber for 100fs pulses at the excitation wavelength of 800nm. For ns pulses at 532nm it exhibits strong optical limiting, indicating possible photonics applications.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2013; 108C:197-210. · 2.10 Impact Factor
  • Article: Three-photon absorption and vibrational spectroscopic study of 2-methylamino-5-chlorobenzophenone.
    D Sajan, K Chaitanya, K Safakath, Reji Philip, T Suthan, N P Rajesh
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    ABSTRACT: In this paper, the vibrational spectral analysis and three-photon absorption properties of an organic material of 2-methylamino-5-chlorobenzophenone have been reported. The geometry and harmonic vibrational wavenumbers are calculated with the help of B3LYP density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology (SQM). SQM force fields have also been used to calculate potential energy distribution (PED) in order to make conspicuous vibrational assignments. The nonlinear absorption properties have been investigated in ethanol solution at 532nm using the Z-scan technique employing laser pulses of 5ns duration. Open aperture Z-scan data reveal the presence of effective three-photon absorption for ns pulses at 532nm resulting in a strong optical limiting behavior, indicating possible photonic applications.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 12/2012; 106C:253-261. · 2.10 Impact Factor
  • Article: Intramolecular charge transfer and Z-scan studies of a semiorganic nonlinear optical material sodium acid phthalate hemihydrate: a vibrational spectroscopic study.
    D Sajan, N Vijayan, K Safakath, Reji Philip, I Hubert Joe
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    ABSTRACT: FT-IR and Raman spectra of the nonlinear optical material sodium acid phthalate hemihydrate crystal have been recorded and analyzed. The equilibrium geometry, bonding features, and harmonic vibrational wavenumbers have been investigated with the help of the B3LYP density functional theory method. A detailed interpretation of the vibrational spectra was carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. The natural bond orbital analysis confirms the occurrence of strong intermolecular hydrogen bonding in the molecule. Nonlinear optical absorption of the sample has been studied at 532 nm using single 5 ns laser pulses, employing the open-aperture Z-scan technique. It is found that the NaAPH molecule is a potential candidate for optical limiting applications.
    The Journal of Physical Chemistry A 06/2011; 115(29):8216-26. · 2.95 Impact Factor
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