The availability of tunable lasers that can excite molecules to selected electronic, vibrational, and rotational levels has added a new dimension to the field of physical chemistry. Our research is probing this dimension by studying how photodissociation reactions and bimolecular reactions depend on and produce molecular degrees of freedom. We are also using laser tools to investigate the electronic and optical properties of molecular materials as well as the structures of biofilms and their chemical properties. For detailed information about our most recent projects, please visit our group webpage.
Photodissociation Dynamics: If enough energy can be imparted to a molecule by laser absorption, the molecule can be made to dissociate into product fragments. We can determine what dynamical constraints the potential energy surfaces impose on the dissociation by measuring, as a function of type and amount of excitation supplied to the parent compound, the distribution of energy in the fragments and the correlations between such vector properties as the recoil velocity direction, the direction of fragment angular momentum, and the direction of the polarization vector of the dissociating light. These measurements are made by using one laser to dissociate the parent compound and a second laser to probe the fragments. Probe techniques include both laser-induced fluorescence and multiphoton ionization. We frequently combine the multiphoton ionization with a technique that produces an image of the dissociation products. The results of our studies provide information about the potential energy surface which controls the fragment motion.
Bimolecular Reactions: Detailed information about the mechanism of chemical reactions can be obtained by measuring the speed and angular distribution for a state-selected product, the differential scattering cross section. We are using a laser imaging technique to measure the three dimensional velocity distribution of reaction products by ionizing the products and then projecting the ions onto a screen, where their position is recorded with a digitizing camera. The reactions receiving our most attention are those important in combustion of fuels and in atmospheric chemistry.
Dynamics of Molecular Materials: In collaboration with Professor Héctor Abruña and his group, we are investigating the optical and electrical properties of molecular materials on solid surfaces using non-linear optical techniques such as sum frequency generation and second harmonic generation. The combination of scanning microscopies and ultrafast lasers provides important tools for understanding how nanoscale materials behave.
Structure and Chemistry of Biofilms: In collaboration with groups in engineering and biology, we are using two-photon scanning laser microscopy to investigate the structures of biofilms and how they sequester heavy metals |
Chandler D. W. and Houston, P. L. Two-dimensional imaging of state-selected
photodissociation products detected by multiphoton ionization,
Journal of Chemical Physics 1987, 87, 1445.
Miller, R. L.; Suits, A. G.; Houston, P.
L.; Toumi, R.; Mack, J. A.; Wodtke, A. M. The 'ozone deficit'
problem: Observation of an O2(X v >=;26) +
O(3P) Channel in the 226-nm Photodissociation
of Ozone, Science 1994, 265, 1831.
Neyer, D. W.; Luo, X.; Burak, I.; Houston,
P. L. Photodissociation Dynamics of State-selected Resonances
of HCO X 2A' Prepared by Stimulated Emission Pumping,
Journal of Chemical Physics 1995, 102, 1645.
Geiser, J. D.; Dylewski, S. M.; Mueller,
J. A.; Wilson, R. J.; Houston, P. L.; Toumi, R. The Vibrational
Distribution of O2(X 3 Sigmag-)
produced in the Photodissociation of Ozone between 226 and 240
and at 266 nm, Journal of Chemical Physics 2000, 112,
1279.
Slinker, J., Bernards, D., Houston, P. L., Abruña,
H. D., Bernhard, S. and Malliaras, G. G. Electroluminescence in Transition Metal Complexes,
Chemical Communications 2003, 2392-2399.
You will find a listing of all publications here.
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