Knowledge Bank

The spectroscopic properties of a new double-minimum state, (2) $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma u+$, of $Na2$ have been determined by studies of infra-red fluorescence recorded at high resolution by Fourier transform spectrometry. Some levels (v,J) of the inner well, and a few upper levels (i.e. levels above the potential maximum) are populated by u.v. lines ($\sim 350$ nm) of krypton-ion and argonion lasers. All vibrational levels of the outer well and many upper levels form the lower states in fluorescence from Rydberg states, e.g. (3s,5s) $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$ populated in two-photon processes (3s,5s) $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+\leftarrow A\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma u+\leftarrow X\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$ by a ring dye-laser. A potential curve has been derived for (2) $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma u+$: the two potential minima lie at $28454.6cm-1,3.688\backslash AA$ and $27879.0cm-1,6.715\backslash AA$ respectively, and the energy at the top of the barrier is about $29220cm-1$ (energies are given relative to the minimum in $X\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$).