The excited state dynamics of resorcinol (1,3-dihydroxybenzene) following UV excitation at a range of pump wavelengths, 278 ≥ λ ≥ 255 nm, have been investigated using a combination of time-resolved velocity map ion imaging and ultrafast time-resolved ion yield measurements coupled with complementary ab initio calculations. After excitation to the 1~1ππ* state we extract a timescale, t1, for excited state relaxation that decreases as a function of excitation energy from 2.70 ns to ~120 ps. This is assigned to competing relaxation mechanisms. Tunnelling beneath the ~1ππ*/~1πσ* conical intersection, followed by coupling onto the dissociative ~1πσ* state, yields H atoms born with high kinetic energy (~5000 cm~(-1)). This mechanism is in competition with an internal conversion process that is able to transfer population from the photoexcited ~1ππ* state back to a vibrationally excited ground state, S0*. When exciting between 264-260 nm a second decay component, t2, is observed and we put forth several possible explanations as to the origins of t2, including conformer specific dynamics.
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