title: A Multipronged Comparative Study of the Ultraviolet Photochemistry of 2-, 3-, and 4-Chlorophenol in the Gas Phase.
abstract: The S1((1)ππ*) state of the (dominant) syn-conformer of 2-chlorophenol (2-ClPhOH) in the gas phase has a subpicosecond lifetime, whereas the corresponding S1 states of 3- and 4-ClPhOH have lifetimes that are, respectively, ∼2 and ∼3-orders of magnitude longer. A range of experimental techniques-electronic spectroscopy, ultrafast time-resolved photoion and photoelectron spectroscopies, H Rydberg atom photofragment translational spectroscopy, velocity map imaging, and time-resolved Fourier transform infrared emission spectroscopy-as well as electronic structure calculations (of key regions of the multidimensional ground (S0) state potential energy surface (PES) and selected cuts through the first few excited singlet PESs) have been used in the quest to explain these striking differences in excited state lifetime. The intramolecular O-H···Cl hydrogen bond specific to syn-2-ClPhOH is key. It encourages partial charge transfer and preferential stabilization of the diabatic (1)πσ* potential (relative to that of the (1)ππ* state) upon stretching the C-Cl bond, with the result that initial C-Cl bond extension on the adiabatic S1 PES offers an essentially barrierless internal conversion pathway via regions of conical intersection with the S0 PES. Intramolecular hydrogen bonding is thus seen to facilitate the type of heterolytic dissociation more typically encountered in solution studies.
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: S J
authors: SJ
authors: Harris
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: T N V
authors: TN
authors: Karsili
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: D
authors: D
authors: Murdock
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: T A A
authors: TA
authors: Oliver
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: A M
authors: AM
authors: Wenge
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: D K
authors: DK
authors: Zaouris
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: M N R
authors: MN
authors: Ashfold
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: J N
authors: JN
authors: Harvey
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: J D
authors: JD
authors: Few
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: S
authors: S
authors: Gowrie
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: G
authors: G
authors: Hancock
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: D J
authors: DJ
authors: Hadden
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: G M
authors: GM
authors: Roberts
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: V G
authors: VG
authors: Stavros
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: G
authors: G
authors: Spighi
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: L
authors: L
authors: Poisson
authors: School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.|Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.|Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.|CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors: B
authors: B
authors: Soep