Knowledge Bank

The previously reported molecular beam electric resonance spectra of $CH3D$ have been reassigned to the forbidden transitions: $J,K,M\to J,K,M-2$. The more common $\Delta M=1$ transitions have also been observed for $J=K=1,2$, and 3. This assignment error led to a factor of two error in the reported electric dipole moment with the correct value being 0.005637 D for the $J=1$ state. All observed transitions are accurately predicted with a conventional hyperfine Hamiltonian generating hyperfine constants for the molecule, including a deuterium quadrupole coupling constant of 185 khz.