SUBMILLIMETER-WAVE SPECTRA OF AMMONIA AND PHOSPHINE

Rotational transitions of different isotopic species of ammonia and phosphine have been observed in the 1/2- to 1-mm region. The frequency of the J=0→1 transition of N14H3 is 572 496.69 ± 0.60 Mc/sec and that for N15H3 is 572 053.18 ± 0.50 Mc/sec. Spectral constants B0 observed for the different isotopic species (in Mc/sec) are: 298 114.68 for N14H3, 297 359.32 for N15H3, 154 173.25 for N14D3, and 153 600.82 for N15D3. Structural dimensions for the ground vibrational state of ammonia obtained by isotopic substitution are 1.0136 for the bond length and 107°3' for the bond angle. For PH3, the rotational constants obtained (in Mc/sec) are: B0=133480.15, DJ=3.95, and DJK=-5.18; for PD3 they are B0=69 471.09, DJ=1.02, and DJK=-1.31. An upper limit of 1/2 Mc has been put on the unknown inversion frequency of PH3. © 1969 The American Physical Society.