Liam M. Duffy
Molecular Reaction Dynamics Probed via Pure Rotational Spectroscopy
Since my arrival at UNCG, my students and I have designed, built and tested an instrument for probing molecular reaction dynamics via pure rotational spectroscopy. The ultrahigh resolution afforded by the technique has allowed us to probe product state distributions with unprecedented “hyper-rovibronic” detail. In chemical reactions, product molecules may be formed in a wide variety of rotational, vibrational, and electronic (rovibronic) states. Measuring and predicting these distributions is the primary way information about the transition state leading to products is determined. In our research we have improved the detail achievable by several orders of magnitude. The energy resolution (<10 -8 cm -1) allows hyperfine states to be revealed in both the ground and excited rovibronic states (i.e. “hyper-rovibronic”).
In 2005 we published our first article, outlining the technical details of the spectrometer, including optimum configurations, noise and sensitivity issues, coherence issues, as well as the relevant issues governing its use in the study of molecular reaction dynamics. This article also gave preliminary results on the photodissociation of OClO, an important reservoir molecule for chlorine radicals in the stratosphere. Over the last couple years, we have completed this study and will publish two student coauthored papers, one on the spectroscopy of vibrationally excited ClO and the other on the nascent vibrational distribution as a function of UV wavelength. This past year, we have also published an article describing a new form of action spectroscopy that takes advantage of the sensitivity if rotational line intensities in a molecular beam to inelastic scattering within the beam. We call the technique BASIS, for Beam Action Spectroscopy via Inelastic Scattering.
Gabriele Santambrogio, Samuel A. Meek, Mark J. Abel, Liam M. Duffy, and Gerard Meijer, Driving Rotational Transitions in Molecules on a Chip, ChemPhysChem, Vol. 12, Issue 10, July 11, 2011, pages 1773-2043
Bobby H. Layne, Liam M. Duffy*, Hans A. Bechtel, Adam H. Steeves, and Robert W. Field, Beam Action Spectroscopy via Inelastic Scattering, Invited Article: Roger E. Miller Memorial Edition of Journal of Physical Chemistry A, 2007, 10.1021/jp0708650, *corresponding author
Liam M. Duffy , Photodissociation dynamics in “hyper-rovibronic” detail: exploring the potential of mm/submm-wave spectroscopy in molecular reaction dynamics experiments., Rev. Sci. Instrum., Vol. 76, 2 September 2005 , p. 093104.