title: Time-resolved photoelectron imaging of excited state relaxation dynamics in phenol, catechol, resorcinol, and hydroquinone.
abstract: Time-resolved photoelectron imaging was used to investigate the dynamical evolution of the initially prepared S(1) (ππ*) excited state of phenol (hydroxybenzene), catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene) following excitation at 267 nm. Our analysis was supported by ab initio calculations at the coupled-cluster and CASSCF levels of theory. In all cases, we observe rapid (<1 ps) intramolecular vibrational redistribution on the S(1) potential surface. In catechol, the overall S(1) state lifetime was observed to be 12.1 ps, which is 1-2 orders of magnitude shorter than in the other three molecules studied. This may be attributed to differences in the H atom tunnelling rate under the barrier formed by a conical intersection between the S(1) state and the close lying S(2) (πσ*) state, which is dissociative along the O-H stretching coordinate. Further evidence of this S(1)/S(2) interaction is also seen in the time-dependent anisotropy of the photoelectron angular distributions we have observed. Our data analysis was assisted by a matrix inversion method for processing photoelectron images that is significantly faster than most other previously reported approaches and is extremely quick and easy to implement.
authors.affiliation: Institute of Photonics & Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Livingstone
authors.forename: James O F
authors.initials: JO
authors.lastname: Thompson
authors.forename: Marija
authors.initials: M
authors.lastname: Iljina
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Donaldson
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Sussman
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Paterson
authors.forename: Dave
authors.initials: D
authors.lastname: Townsend
mesh_terms: D002396:Catechols / Q000737:chemistry*; D006873:Hydroquinones / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010636:Phenols / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012118:Resorcinols / Q000737:chemistry*; D013997:Time Factors
chemical_list: D002396:Catechols; D006873:Hydroquinones; D010636:Phenols; D012118:Resorcinols; C034221:catechol; C031927:hydroquinone; C031389:resorcinol