Millimeter- and submillimeter-wavelength spectrum and molecular constants of T2O

The rotational spectrum of T₂O in the ground vibrational state has been measured with high-resolution microwave techniques in the 80-640-GHz region. Forty-six previously unreported transitions have been measured and assigned. Analysis of these results and the six previously observed lines yielded the following rotation and distortion parameters (in MHz) of the Watson formulation: 𝒜=338810.923±0.076, ℬ=145665.417±0.044, 𝒞=100259.415±0.044, ${\Delta }_J=4.145597\pm 0.0014$, ${\Delta }_{JK}=-22.03898\pm 0.008$, ${\Delta }_K=144.13766\pm 0.006$, ${\delta }_J=1.609823\pm 0.0008$, and ${\delta }_K=5.44092\pm 0.01$. The usual distortion-free rotational constants derived from these are (in MHz) A′=338808.0, B′=145631.9, and C′=100291.9. The effective ground-state structures obtained for T₂O are 0.9623 \AA{} for the bond length and 104.6° for the bond angle. The observed inertial defect Δ=0.0772 amu Ų agrees well with the theoretically derived value of 0.0753 amu Ų.