Knowledge Bank

Discrete features associated with transitions of both the T-shaped and linear Ar$\cdots$I$2(X,v\prime \prime$=0) complexes are observed in laser-induced fluorescence and action spectroscopy experiments performed throughout the I$2$ {\it B}$-${\it X} electronic region. The binding energy of the linear conformer is directly measured to be 250(2) cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$, 10 to 15 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ greater than that of the T-shaped conformer. Continuum signals are observed in the spectra that continue to energies well above the I$2$({\it B}) dissociation limit. Our results indicate that the continuum signals can be attributed to transitions of the linear Ar$\cdots$I$2$({\it X},{\it v}=0) complex to the inner, repulsive walls of many Ar $+$ I$2$({\it B},{\it v}) intermolecular potentials. The excited state complexes are thus very short lived and undergo direct dissociation into Ar $+$ I$2$({\it B},{\it v}) products. There is no evidence for the previously proposed one-atom caging mechanism.