Bound orbiting states of benzene-Ar and evidence for reversible intramolecular vibrational energy redistribution within the complex

We have explored the proposition that emission from bound orbiting states of aromatic van der Waals complexes occurs where the free aromatic emits. Pumping (6(1)) over bar in benzene-Ar is predicted to lead, via intramolecular vibrational energy redistribution (IVR), that are above the barrier to bound orbital motion. to excitation in van der Waals modes associated with (16(1)) over bar that are above the barrier bound orbital motion. The (6(1)) over bar dispersed fluorescence spectrum shows a red-shaded, broad band with a maximum 21 cm(-1) to the blue of the expected <(6(1)(0)16(1)(1))over bar> transition, where the <(6(1)(0)16(1)(1))over bar> band of free benzene occurs. The time dependence of the parent and growth bands in the (6(1)) over bar spectrum suggests that IVR from this level is reversible. (C) 2004 Elsevier B.V. All rights reserved.