| Abstract: | High resolution (0.004cm-1 instrumental bandwidth) interferometric Fourier transform infrared spectra of 14ND3 were obtained on a BOMEM DA002 spectrometer under essentially Doppler limited conditions. An analysis is reported of the ND3 stretching fundamentals with band centres at EQUATION]1 0 (s ← a) = (2420.056 ± 0.001)cm?1, EQUATION]1 0(a ← s) = (2420.650 ± 0.001)cm?1, EQUATION]3 0(a ← a) = (2563.8840 ± 0:0005)cm?1 and EQUATION]3 0 (s ← s) = (2563.9161 ± 0.0005)cm?1, with inversion tunnelling splittings ΔEQUATION]1 = 0.5412cm?1 and ΔEQUATION]3 = 0.0209cm?1 in the vibrationally excited levels. About 50 parameters of the effective Hamiltonian for this band system could be determined accurately. Assignments were established with certainty by means of ground state combination differences. The results are important for and are discussed in relation to the mode selective inhibition and promotion of inversion at the nitrogen atom by exciting ND stretching vibrations, and treatments of isotope e? ects on inversion of ammonia by means of effective Hamiltonians and true molecular Hamiltonians on high dimensional potential hypersurfaces. |
