Department

• Chemistry and Biochemistry

Position

• Assistant Professor

Articles

• Photodissociation of the N2-NO complex between 225.8 and 224.0 nm. (accepted), Journal of Physical Chemistry A, 2021
• Investigation of O2-X (X = Pyrrole or Pyridine) Cluster Photodissociation Near 226 nm., Journal of Physical Chemistry A, 124, 10152-10161, 2020
• Sheehan, Sean M., Parsons, Bradley F., Yen, Terry A., Furlanetto, Michael R., Neumark, Daniel M. Anion photoelectron spectroscopy of C5H-, Journal of Chemical Physics, 128, 174301, 2008
• Sheehan, Sean M., Parsons, Bradley F., Zhou, Jia, Garand, Etienne, Yen, Terry A., Moore, David T., Neumark, Daniel M. Characterization of cyclic and linear C3H- and C3H via anion photoelectron spectroscopy, Journal of Chemical Physics, 128, N.PAG, 2008

Research and Scholarship Interests

• 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.

Current Research Projects

• Currently my lab is exploring two projects.  First, I am interested in the photochemistry of O2-M complexes (M = organic species).  These systems provide information on the O2 excited states formed by collision complexes following photoexcitation.  Currently, my lab is most interested in nitrogen containing organic species, which are similar to some organic species found in complex biological molecules.  The second project in my lab involves studies of complexes involving atmospheric species.  This project provides an opportunity to study gas collision complexes from a fixed geometry.  Currently my lab has an active project to investigate the X-NO (X = N2, O2) complexes as a means of better understanding collisional quenching of the NO (A) state, which is used in laser induced fluorescence monitoring of atmospheric NO.