SOLVENT AND PHASE DEPENDENCE OF FERMI RESONANCE IN AMMONIA

The 3300-cm-1 region of the Raman spectrum of ammonia in the solvents benzene, carbon tetrachloride, and pentane and in the vapor phase has been analyzed by using the damped coupled oscillator model for Fermi resonance. The experimental spectra in both phases were fit quite well by using only four adjustable parameters in the model. It was found that the Fermi resonance interaction constant, the uncoupled frequencies, and the line widths varied smoothly between the values of the neat liquid and the gas phase upon dilution, demonstrating the same trends in all three solvents studied. These results indicate that ammonia-ammonia interactions are absent at sufficiently low concentration and, further, that there appears to be little, if any, residual hydrogen bonding of ammonia in any of the systems studied. © 1979 American Chemical Society.