Current Research

Research in the Douberly group employs infrared laser spectroscopy to study neutral and ionic molecular assemblies isolated in ultra-low temperature (0.4 Kelvin) helium nanodroplets.  Liquid helium droplets are formed by the condensation of gaseous helium in a cryogenic nozzle expansion.  The droplets are approximately 10 nm in diameter, and molecular assemblies are formed within each droplet by the sequential “pick up” of individual atoms or molecules.  The interaction between the molecular solute and the helium solvent is extremely weak due to the quantum nature of helium at 0.4 Kelvin.  As a result, helium droplets provide a unique environment to probe the structural and dynamical properties of the isolated species with a variety of emerging methods in high resolution laser spectroscopy. 

        The Douberly group is using this methodology to address a diverse set of fundamental problems in chemical physics.  The general strategy of their research effort is to boil down critically important mesoscale and bulk phenomena to the cluster limit, and probe with high resolution and precision the fundamental molecular physics that underpin the larger scale phenomena.  For example, they are investigating the mechanisms associated with several key elementary reactions in atmospheric and combustion chemistry.  Helium mediated, low temperature reactions involving hydrocarbon radicals and molecular oxygen are probed with infrared laser spectroscopy.  These measurements identify the structural configuration of key intermediates along the reaction path, along with the associated product branching ratios.  One of the major impacts of this work is that these studies provide important benchmarks for theoretical studies, in which the ultimate goal is to establish a predictive combustion modeling capability that allows for the design and optimization of next generation engine technologies.  Several reactions have been probed that involve the hydroxyl radical (OH) and other small atmospherically relevant species such as water, oxygen, and ozone, which are critically important to our understanding of the atmospheric ozone balance and tropospheric atmospheric chemistry in general.  Once again, these measurements will provide a basis upon which predictive atmospheric chemistry models are developed.

        The low temperature and rapid cooling provided by helium droplets results in a perfectly suited medium to bring otherwise transient reactants together in a way such that they are stabilized in high energy metastable configurations.  The products that result from vibrational or electronic excitation of the metastable reactants can be interrogated with infrared or electronic spectroscopy.  Multi-laser schemes allow for a systematic study of how product branching ratios change as vibrational energy is placed into different modes of the reacting system.  A long term goal of the Douberly group’s work is to develop helium nanodroplet isolation into a general technique for studying the laser driven chemistry of highly reactive species near absolute zero.

        Experiments are also underway in the Douberly lab in which small water clusters and mixed acid-water clusters are assembled in the low temperature liquid helium environment.  Here they use infrared laser spectroscopy to probe the evolution of the spectral signatures associated with the formation and trapping of metastable, non-equilibrium cluster geometries, and ultimately the onset of acid ionization, which is a fundamental issue underlying a range of bulk phenomena associated with biochemistry.  Furthermore, they employ this methodology to trap model biomolecule systems and to investigate their three dimensional structure, preferred conformations, rearrangements upon solvation, and thermochemistry at a high level of detail.  Indeed, the correlation between the structure of biological macromolecules and their function is well recognized, and the development of high resolution structural probes is essential if we are to achieve a microscopic understanding of this relationship. This is another important fundamental area that they foresee contributing significantly to in the coming years.

Selected Publications

Leavitt, C. M. ; Moore, K. B. ; Raston, P. L. ; Agarwal, J. ; Moody, G. H. ; Shirley, C. C. ; Schaefer, H. F. ; Douberly, G. E. Liquid Hot NAGMA Cooled to 0.4 K: Benchmark Thermochemistry of a Gas-Phase Peptide. The Journal of Physical Chemistry A 2014, 118, 9692 - 9700.
Raston, P. L. ; Douberly, G. E. ; Jäger, W. Single and double resonance spectroscopy of methanol embedded in superfluid helium nanodroplets. The Journal of Chemical Physics 2014, 141, 044301.
Leavitt, C. M. ; Moradi, C. P. ; Stanton, J. F. ; Douberly, G. E. Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene. The Journal of Chemical Physics 2014, 140, 171102.
Raston, P. L. ; Liang, T. ; Douberly, G. E. Observation of the Q(3/2) Lambda-doublet transitions for X-doublet-PI-3/2 OD in helium nanodroplets. Molecular Physics 2014, 112, 301-303.
Leavitt, C. M. ; Moradi, C. P. ; Acrey, B. W. ; Douberly, G. E. Infrared laser spectroscopy of the helium-solvated allyl and allyl peroxy radicals. Journal of Chemical Physics 2013, 139, 234301.
Liang, T. ; D. Magers, B. ; Raston, P. L. ; Allen, W. D. ; Douberly, G. E. Dipole Moment of the HOOO Radical: Resolution of a Structural Enigma. Journal of Physical Chemistry Letters 2013, 4, 3584-3589.
Moradi, C. P. ; Morrison, A. M. ; Klippenstein, S. J. ; C. Goldsmith, F. ; Douberly, G. E. Propargyl + O2 Reaction in Helium Droplets: Entrance Channel Barrier or Not?. Journal of Physical Chemistry A 2013, 117, 13626-13635.
Obi, E. I. ; Leavitt, C. M. ; Raston, P. L. ; Moradi, C. P. ; Flynn, S. D. ; Vaghjiani, G. L. ; Boatz, J. A. ; Chambreau, S. D. ; Douberly, G. E. Helium Nanodroplet Isolation and Infrared Spectroscopy of the Isolated Ion-Pair 1-Ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide. Journal of Physical Chemistry A 2013, 117, 9047-9056.
Raston, P. L. ; Agarwal, J. ; Turney, J. M. ; Schaefer, III, H. F. ; Douberly, G. E. The ethyl radical in superfluid helium nanodroplets: Rovibrational spectroscopy and ab initio computations. Journal of Chemical Physics 2013, 138, 194303.
Raston, P. L. ; Douberly, G. E. Rovibrational spectroscopy of formaldehyde in helium nanodroplets. Journal of Molecular Spectroscopy 2013, 292, 15-19.
Raston, P. L. ; Liang, T. ; Douberly, G. E. Infrared spectroscopy and tunneling dynamics of the vinyl radical in He-4 nanodroplets. Journal of Chemical Physics 2013, 138, 174302.
Gomez, L. F. ; Sliter, R. ; Skvortsov, D. ; Hoshina, H. ; Douberly, G. E. ; Vilesov, A. F. Infrared Spectra in the 3 micron Region of Ethane and Ethane Clusters in Helium Droplets. Journal of Physical Chemistry A 2013, 117, 13648-13653.
Raston, P. L. ; Liang, T. ; Douberly, G. E. Anomalous Lambda-Doubling in the Infrared Spectrum of the Hydroxyl Radical in Helium Nanodroplets. J. Phys. Chem. A 2013, 117, 8103-8110.
Morrison, A. M. ; Liang, T. ; Douberly, G. E. Automation of an “Aculight” continuous-wave optical parametric oscillator. Review of Scientific Instruments 2013, 84, 013102.
Morrison, A. M. ; Raston, P. L. ; Douberly, G. E. Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets. The Journal of Physical Chemistry A 2013, 117, 11640-11647.
Liang, T. ; Raston, P. L. ; Douberly, G. E. Helium Nanodroplet Isolation Spectroscopy and ab Initio Calculations of HO3(O2)n Clusters. ChemPhysChem 2013, 14, 764-770.
Raston, P. L. ; Liang, T. ; Douberly, G. E. Infrared spectroscopy of HOOO and DOOO in 4He nanodroplets. The Journal of Chemical Physics 2012, 137, 184302.
Liang, T. ; Douberly, G. E. On the Al+HCN reaction in helium nanodroplets. Chemical Physics Letters 2012, 551, 54 - 59.
Morrison, A. M. ; Agarwal, J. ; Schaefer, H. F. ; Douberly, G. E. Infrared Laser Spectroscopy of the CH3 OO Radical Formed from the Reaction of CH3 and O2 within a Helium Nanodroplet. The Journal of Physical Chemistry A 2012, 116, 5299 - 5304.
Liang, T. ; Flynn, S. D. ; Morrison, A. M. ; Douberly, G. E. Quantum Cascade Laser Spectroscopy and Photoinduced Chemistry of Al–(CO)n Clusters in Helium Nanodroplets. The Journal of Physical Chemistry A 2011, 115, 7437 - 7447.
Douberly, G. E. ; Stiles, P. L. ; Miller, R. E. ; Schmied, R. ; Lehmann, K. K. (HCN)m-Mn (M = K, Ca, Sr): Vibrational Excitation Induced Solvation and Desolvation of Dopants in and on Helium Nanodroplets. Journal of Physical Chemistry A 2010, 114, 3391-3402.
Flynn, S. D. ; Skvortsov, D. ; Morrison, A. M. ; Liang, T. ; Choi, M. Y. ; Douberly, G. E. ; Vilesov, A. F. Infrared Spectra of HCl-H2O Clusters in Helium Nanodroplets. Journal of Physical Chemistry Letters 2010, 1, 2233-2238.
Morrison, A. M. ; Flynn, S. D. ; Liang, T. ; Douberly, G. E. Infrared Spectroscopy of (HCl)m(H2O)n Clusters in Helium Nanodroplets: Definitive Assignments in the HCl Stretch Region. Journal of Physical Chemistry A 2010, 114, 8090-8098.
Stiles, P. L. ; Douberly, G. E. ; Miller, R. E. High-resolution infrared spectroscopy of Mg-HF and Mg-(HF)2 solvated in helium nanodroplets. Journal of Chemical Physics 2009, 130, 184313.
Douberly, G. E. ; Miller, R. E. Vibrational dynamics of the linear and bent isomers of HF-N2O trapped in 0.4 K helium nanodroplets. Chemical Physics 2009, 361, 118-124.
Merritt, J. M. ; Douberly, G. E. ; Stiles, P. L. ; Miller, R. E. Infrared spectroscopy of prereactive aluminum-, gallium-, and indium-HCN entrance channel complexes solvated in helium nanodroplets. Journal of Physical Chemistry A 2007, 111, 12304-12316.
Paesani, F. ; Whaley, K. B. ; Douberly, G. E. ; Miller, R. E. Rovibrational spectra for the HCCCN-HCN and HCN-HCCCN binary complexes in 4He Droplets. Journal of Physical Chemistry A 2007, 111, 7516-7528.
Douberly, G. E. ; Merritt, J. M. ; Miller, R. E. Infrared-infrared double resonance spectroscopy of the isomers of acetylene-HCN and cyanoacetylene-HCN in Helium nanodroplets. Journal of Physical Chemistry A 2007, 111, 7282-7291.
Douberly, G. E. ; Miller, R. E. Rotational dynamics of HCN-M (M = Na, K, Rb, Cs) van der waals complexes formed on the surface of Helium nanodroplets. Journal of Physical Chemistry A 2007, 111, 7292-7302.
Choi, M. Y. ; Douberly, G. E. ; Falconer, T. M. ; Lewis, W. K. ; Lindsay, C. M. ; Merritt, J. M. ; Stiles, P. L. ; Miller, R. E. Infrared spectroscopy of helium nanodroplets: novel methods for physics and chemistry. International Reviews in Physical Chemistry 2006, 25, 15-75.
Lindsay, C. M. ; Douberly, G. E. ; Miller, R. E. Rotational and vibrational dynamics of H2O and HDO in helium nanodroplets. Journal of Molecular Structure 2006, 786, 96-104.
Douberly, G. E. ; Merritt, J. M. ; Miller, R. E. IR-IR double resonance spectroscopy in helium nanodroplets: Photo-induced isomerization. Physical Chemistry Chemical Physics 2005, 7, 463-468.
Douberly, G. E. ; Miller, R. E. The isomers of HF-HCN formed in helium nanodroplets: Infrared spectroscopy and ab initio calculations. Journal of Chemical Physics 2005, 122, 024306.
Merritt, J. M. ; Douberly, G. E. ; Miller, R. E. Infrared-infrared-double resonance spectroscopy of cyanoacetylene in helium nanodroplets. Journal of Chemical Physics 2004, 121, 1309-1316.
Douberly, G. E. ; Miller, R. E. The growth of HF polymers in helium nanodroplets: Probing the barriers to ring insertion. Journal of Physical Chemistry B 2003, 107, 4500-4507.
Douberly, G. E. ; Nauta, K. ; Miller, R. E. The infrared spectrum of acetylene-HF in helium nanodroplets. Chemical Physics Letters 2003, 377, 384-390.