Observation of a shape resonance in thea3∑u+state of7Li2

Abstract

Using the most accurate potential curves available for the $a{}^{3}{\ensuremath{\sum}}_{u}^{+}$ and $X{}^{1}{\ensuremath{\sum}}_{g}^{+}$ states of lithium molecules, we compute the positions of shape resonances. We also calculate the deexcitation probability from a bound level ${v}^{\ensuremath{'}}$ with rotational number ${N}^{\ensuremath{'}}$ to the continuum of the lower state, and conclude that a shape resonance should be measurable for the transition $2{}^{3}{\ensuremath{\prod}}_{g}\ensuremath{\rightarrow}a{}^{3}{\ensuremath{\sum}}_{u}^{+}$. Such a shape resonance has been identified from the spectra of the transition from the ${v}^{\ensuremath{'}}{=2,N}^{\ensuremath{'}}=4$ level of $2{}^{3}{\ensuremath{\prod}}_{g}$ into the ${N}^{\ensuremath{''}}=4$ continuum of $a{}^{3}{\ensuremath{\sum}}_{u}^{+}$. Its position is in good agreement with the theoretical prediction.