Molecular Dipole Moments and Stark Effects. II. Stark Effects in OCS

The dipole moments of OCS for several isotopic species and vibrational states have been determined from the Stark splitting of the $J=1\mathrm{}\to 2$ rotational transition. The value of the ${\mathrm{O}}^{16}$ ${\mathrm{C}}^{12}$ ${\mathrm{S}}^{32}$ moment is 0.7085±0.004 debye units. The ${\mathrm{O}}^{16}$ ${\mathrm{C}}^{12}$ ${\mathrm{S}}^{34}$ and ${\mathrm{O}}^{16}$ ${\mathrm{C}}^{13}$ ${\mathrm{S}}^{32}$ moments differ from this by less than 0.2 percent. The ${\mathrm{O}}^{16}$ ${\mathrm{C}}^{12}$ ${\mathrm{S}}^{32}$ molecule in the excited bending mode ($v_2=1\mathrm{}$) is treated formally as a slightly asymmetric top which produces a doublet. Measurement of Stark effect for these lines gives a dipole moment of 0.700±0.004 debye. Upon introduction of a Stark voltage, two weak lines appear on either side of the doublet $v_2=1\mathrm{}$. They are explained as transitions involving the doublet levels which are forbidden in zero field, but allowed upon the introduction of a perturbing field.