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Investigation of Polarized Infrared Spectra of the Hydrogen Bond in Molecular Crystls. New Spectra Effects in the Vibrational Spectroscopy of Hydrogen Bonded Systems

Flakus H.

Polish Journal of Chemistry

2003

Vol. 77 / nr 5

489-517

Areview of the experimental as well as of the theoretical studies, performed on the area of the infrared spectroscopy of hydrogen bonded molecular crystals, is given. Discussion of some physical phenomena is presented, responsible for basic spectral effects registered in the infrared spectra, as breaking of vibrational dipole selection rules in the IR spectra, linear dichroic as well as temperature effects, observed in the frequency range of the proton stretching vibrations. Also some newly recognized H/D isotopic effects for hydrogen bonded systems are presented, deduced from a quantitative analysis of the polarized spectra in the IR, namely the so called isotopic "self-organization" effects and the "long-range" H/D isotopic effects.

The influence of Fermi resonance and of isotopic substitution on the infrared spectra of hydrogen bonded crystals

Ratajczak H., Orville-Thomas W. J., Yaremko A., Ostrovskii D.

Bulletin of the Polish Academy of Sciences. Chemistry

1999

Vol. 47, No. 3

193-208

A theoretical approach, which takes into account both the Fermi resonance effect and strong anharmonic interaction between high-frequency v(XH) stretching vibra-tions and the lattice phonons, has been used to explain the IR spectral profiles of NaHF2 , HCrO2 and HCoO2 crystals and their deuterated analogues. Good correlation between the theoretical and experimental spectra has been obtained. It is shown that qualitative changes in the IR spectra of the crystals arising with isotopic substitution are mainly due to the change of the resonance conditions. It is found that in DCrO2 and DCoO2 crystals Fermi resonance is strong, whereas in HCrO2 and HCoO2 materials it is weak.