Bradley F . Parsons, PhD

Research Focus

I am interested in the photochemistry of small gas phase complexes.  In my lab, a complex between two gas phase species is formed in a pulsed supersonic expansion.  The supersonic expansion cools internal molecular motions and may condense species into small clusters.  The resulting molecular beam is skimmed and passed into a mass spectrometer that uses conventional velocity map imaging (VMI) ion optics.  Inside the VMI ion optics, the molecular beam is intersected by a tunable pulsed laser that photolyzes the complex resulting in a variety of photofragments.  The photofragments are then ionized by the same laser pulse and the resulting cations are projected onto a 2D position sensitive detector.  Ions impact the detector according to their center-of-mass velocity from the original photodissociation and an image of the detector is recorded using a CCD.  The 2D image corresponds to the Abel transform of the original 3D photofragment distribution.  Thus, from the 2D image, the original 3D center-of-mass velocity distribution is obtained and then converted into a center-of-mass recoil kinetic energy distribution P(ET).  The resulting P(ET) contains information on the internal state(s) of the partner fragment formed during photolysis of the complex.