Exploring conical intersections through high resolution photofragment translational spectroscopy

High resolution measurements of the kinetic energies of H atom fragments formed during UV photolysis of gas phase imidazole, [1,2] pyrrole, [3] phenol [4] and thiophenol molecules show that: (i) X-H (X = N, O, S) bond fission is an important non-radiative decay process from the $^{1}\pi \sigma $* excited states in each of these molecules, and (ii) that the respective co-fragments (imidazolyl, pyrrolyl, phenoxyl and thiophenoxyl) are formed in very limited sub-sets of their available vibrational states. Identification of these product states yields uniquely detailed insights into the vibronic couplings involved in the photo-induced evolution from parent molecule to ultimate fragments. \newline \newline [1] M.N.R. Ashfold, B. Cronin, A.L. Devine, R.N. Dixon and M.G.D. Nix, \textit{Science }(2006), \textbf{312}, 1637. \newline [2] A.L. Devine, B. Cronin, M.G.D. Nix and M.N.R. Ashfold, \textit{J. Chem. Phys.} (in press). \newline [3] B. Cronin, M.G.D. Nix, R.H. Qadiri and M.N.R. Ashfold, \textit{Phys. Chem. Chem. Phys.} (2004), 6, 5031. \newline [4] M.G.D. Nix, A.L. Devine, B. Cronin, R.N. Dixon and M.N.R. Ashfold, \textit{J. Chem. Phys.} (2006), \textbf{125}, 133318.