The nu(1) and nu(3) bands of ND3

High resolution (0.004cm(-1) instrumental bandwidth) interferometric Fourie r transform infrared spectra of (ND3)-N-14 were obtained on a BOMEM DA002 s pectrometer under essentially Doppler limited conditions. An analysis is re ported of the ND3 stretching fundamentals with band centres at <(nu)over ti lde>(0)(1) (s <-- a) = (2420.056 +/- 0.00 cm(-1), <(nu)over tilde>(0)(3) (a <-- s) = (2420.650 +/- 0.001) cm(-1) <(nu)over tilde>(0)(3)(a <-- a) = (25 63.8840 +/- 0.0005)cm(-1) and <(nu)over tilde>(0)(3) (S <-- S) = (2563.9161 +/- 0.0005) cm(-1) with inversion tunnelling splittings Delta<(nu)over til de>(1) = 0.5412cm(-1) and Delta<(nu)over tilde>(3) = 0.0209cm(-1) in the vi brationally excited levels. About 50 parameters of the effective Hamiltonia n for this band system could be determined accurately. Assignments were est ablished with certainty by means of ground state combination differences. T he results are important for and are discussed in relation to the mode sele ctive inhibition and promotion of inversion at the nitrogen atom by excitin g ND stretching vibrations, and treatments of isotope effects on inversion df ammonia by means of effective Hamiltonians and true molecular Hamiltonia ns on high dimensional potential hypersurfaces.