The 2 1 (A 1 ; 647.13 cm À1 ), 2 2 (A 1 ; 1292:26 cm À1 ) and 2 1 4 1 (E; 1138:28 cm À1 ) excited states of 14 NF 3 have been studied by highresolution FTIR spectroscopy with a resolution between 2.3 and 3:0 Â 10 À3 cm À1 , and by millimeter-wave (MMW) spectroscopy. For the 2 1 state, 3380 non-zero weighted (NZW) m 2 infrared (IR) transitions (J max ¼ K max ¼ 70) and 59 MMW transitions (J max ¼ 27, K max ¼ 21) were fitted together, with respective rms deviations r IR ¼ 0:142 Â 10 À3 cm À1 and r MMW ¼ 28 kHz, using an unperturbed model up to sextic centrifugal distortion constants. The lower state parameters were constrained to those of the ground state. Similarly we have fitted 2181 NZW transitions (J max ¼ K max ¼ 60) of the 2m 2 À m 2 hot band merged with 54 MMW transitions (J max ¼ 21, K max ¼ 13) measured in the 2 2 state and employing the 2 1 parameters for the lower state. Respective rms deviations were r IR ¼ 0:263 Â 10 À3 cm À1 and r MMW ¼ 58 kHz. The anharmonicity constant x 22 ¼ À1:00606ð1Þ cm À1 was determined. The v 2 ¼ 2 state is better determined by the 2m 2 À m 2 rather than the obtained 2m 2 IR data owing to the weakness of 2m 2 . To the contrary the strong and isolated m 2 þ m AE1 4 combination band is much better suited to probe the 2 1 4 1 state than the m 2 þ m AE1 4 À m AE1 4 hot band. Therefore 4375 NZW IR lines (J max ¼ K max ¼ 69) of m 2 þ m 4 and 119 MMW transitions belonging to the 2 1 4 1 state with J max ¼ K max ¼ 13 were fitted together using the same model as for the m 4 fundamental band. This model takes into account l(2, 2), l(2, )1), l(2, )4), and (0, 6) intravibrational interactions when the D reduction of the Hamiltonian is employed. The corresponding rms of deviations were r IR ¼ 0:270 Â 10 À3 cm À1 and r MMW ¼ 227 kHz; similar rms values were also obtained for Q and QD reductions refining uniformly 22 parameters. The anharmonicity constant x 24 ¼ À2:27995ð3Þ cm À1 was determined.