Knowledge Bank

The rotational transition $J=3\leftarrow 2$ of SO in the a $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta$ state has been detected at $127770.45\pm 0.15$ MHz with microwave spectroscopy. This is the first observation of microwave rotational transition for a molecule in an electronically excited state. The rotational constant was found to be $Bo=21295.1\pm 0.7$ MHz and the dipole moment obtained was $1.336\pm 0.045$ D. Gas-phase EPR spectroscopy at 4460 MHz in the C-band region has revealed five lines of the six allowed transitions for the rotationally excited J = 3 level of SO in the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta$ state besides four lines for the J = 2 ground level. The use of the C band in place of the X band (ca. 9 GHz) conventionally employed doubles the measurable resonance region and hence enables one to determine molecular constants more precisely. The analysis of the EPR spectra has resulted in the l-uncoupling constant , using the theoretical values of $gL=1,00000$ and $gzN=-0.00027$, as well as the rotational constant $Bo$ determined above, and assuming finite perturbations only from the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Pi$ states. If only one $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Pi$ state contributes dominantly to the perturbation, the perturbing state lies $12000cm-1$ above the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta$ state under pure precession hypothesis.