One-to-Two Millimeter Wave Spectroscopy. V. PH3and PD3

The $J=0\mathrm{}\to 1$ rotational transition of P${\mathrm{H}}_3$ has been measured at ${\nu }_0=266\mathrm{}944.0\pm 1.0$ Mc/sec ($\lambda =1.12\mathrm{}$ mm). With $D_J=3.15\mathrm{}$ Mc/sec from infrared spectroscopy, this measurement yields $B_0=133\mathrm{}478.3$ Mc/sec. Similarly, the 0→1 transition of P${\mathrm{D}}_3$ was measured at ${\nu }_0=138\mathrm{}937.98\pm 0.30$ Mc/sec ($\lambda =2.16\mathrm{}$ mm) and $B_0=69\mathrm{}470.41$ Mc/sec was obtained by using $D_J=0.71\mathrm{}$ Mc/sec from infrared spectroscopy. The bond lengths in the two isotopic forms were found to be slightly different with $d_{\mathrm{PH}}=1.4206\mathrm{}\pm 0.005$ A and $d_{\mathrm{PD}}=1.4166\mathrm{}\pm 0.005$ A.