Featured publication in the Journal of Chemical Physics, using VMI to investigate the photodissociation dynamics of small molecules

Photek and the University of Bristol collaborated on the development of the Velocitas VMI Double Prime ion optics, and our latest publication in the Journal of Chemical Physics uses the new and improved ion optics to explore the near ultraviolet photodissociation dynamics of gas phase 2-bromo and 2-iodothiophene molecules.

Near ultraviolet photochemistry of 2-bromo- and 2-iodothiophene: Revealing photoinduced ring opening in the gas phase? Barbara Marchetti, Tolga N V Karsili, Orla Kelly, Panos Kapetanopoulos and Michael N R Ashfold J. Chem. Phys. 142, 224303 (2015) http://scitation.aip.org/content/aip/journal/jcp/142/22/10.1063/1.4921315

Near ultraviolet photochemistry of 2-bromo- and 2-iodothiophene: Revealing photoinduced ring opening in the gas phase? Velocity map imaging methods, with a new and improved ion optics design, have been used to explore the near ultraviolet photodissociation dynamics of gas phase 2-bromo- and 2-iodothiophene molecules. In both cases, the ground (X) and spin-orbit excited (X*) (where X = Br, I) atom products formed at the longest excitation wavelengths are found to recoil with fast, anisotropic velocity distributions, consistent with prompt C-X bond fission following excitation via a transition whose dipole moment is aligned parallel to the breaking bond. Upon tuning to shorter wavelengths, this fast component fades and is progressively replaced by a slower, isotropic recoil distribution. Complementary electronic structure calculations provide a plausible explanation for this switch in fragmentation behaviour-namely, the opening of a rival C-S bond extension pathway to a region of conical intersection with the ground state potential energy surface. The resulting ground state molecules are formed with … Read more here.