Ongoing Projects in the Douberly Lab

The Douberly group has leveraged the sequential pick-up technique developed by Scoles to investigate the mechanisms associated with several key elementary atmospheric and combustion reactions carried out inside low temperature helium droplets.  The rational for these studies is that spectroscopic measurements carried out downstream from the pick-up zones are capable of identifying the structural configuration of key intermediates along the reaction path, along with the associated product branching ratios.  The outcome of low temperature reactions involving hydrocarbon radicals and O2,4,5,12 or the hydroxyl radical (OH) and O2,13 have been probed with this methodology.  For example, a series of studies on the OH + O2 helium-mediated reaction revealed the barrierless formation of trans-HOOO,13-15 which was inconsistent with theoretical studies that had predicted a large entrance channel barrier above the reactant asymptote.  Higher level multireference configuration interaction computations of this system carried out by others confirmed the barrierless reaction path implied by Douberly’s experiments.  IR laser Stark spectroscopy of trans-HOOO revealed inertial components of the permanent electric dipole moment that were inconsistent with computations at the equilibrium geometry, consistent with a floppy species undergoing large-amplitude torsional motion.15  These experimental dipole components provided a stringent benchmark for theoretical computations of the ground state wavefunction, which eventually resulted in definitive computations of the dissociation energy and atmospheric abundance of this species.15

            Measurements have been reported in which dipeptides,16 ionic liquids17 or mixed acid-water clusters17,18 are assembled within helium droplets.  A two-stage oven source was developed which allowed for high-precision measurements of the gas-phase interconversion thermodynamics of the model di-peptide N-acetylglycine methylamide.16  Polarization spectroscopy of the ionic liquid 1Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide revealed a dipole moment of ~12 Debye, confirming definitively that these types of systems evaporate as intact ion-pairs.17  IR laser spectroscopy was used to probe the evolution of the spectral signatures associated with the formation and trapping of non-equilibrium (HCl)n-(H2O)m cluster geometries.18,19  This study was reported in collaboration with Andrey Vilesov and provided critical insights into controversial previous measurements of the onset of acid ionization in small acid-water clusters.  More recently, a paper on the formation of exotic hydrogen-bonded water networks in helium droplets was published in the Journal of the American Chemical Society.20  The range of systems studied during Douberly’s independent career is both a testament to the versatility of the helium droplet method and the creativity of his research group.

 

  1. Morrison, A.M.; Raston, P.L.; Douberly, G.E., “Rotational relaxation dynamics of the methyl radical in helium nanodroplets” Journal of Physical Chemistry A, (2013), 117, 11640-11647. 

  2. 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.

  3. Raston, P.L.; Liang, T.; Douberly, G.E., “Infrared spectroscopy and tunneling dynamics of the vinyl radical in 4He Nanodroplets” Journal of Chemical Physics, (2013), 138, 174302.

  4. Moradi, C.P.; Morrison, A.M.; Klippenstein, S.J.; Goldsmith, C.F.; Douberly, G.E., “The propargyl + O2 reaction in helium droplets: entrance channel barrier or not?” Journal of Physical Chemistry A, (2013), 117, 13626-13635.

  5. 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.

  6. Raston, P.L.; Liang, T.; Douberly, G.E., “Anomalous L-doubling in the infrared spectrum of the hydroxyl radical in helium nanodroplets” Journal of Physical Chemistry A, (2013), 117, 8103-8110.

  7. Leavitt, C.M.; Moradi, C.P.; Stanton, J.F.; Douberly, G.E., “Communication: Helium Nanodroplet Isolation and Rovibrational Spectroscopy of Hydroxymethlyene” Journal of Chemical Physics, (2014), 140, 171102.

  8. Broderick, B.M.; McCaslin, L.; Moradi, C.P.; Stanton, J.F.; Douberly, G.E. “Reactive Intermediates in 4He Nanodroplets: Infrared Laser Stark Spectroscopy of Dihydroxycarbene” Journal of Chemical Physics, (2015), 142, 144309.

  9. Raston, P.L.; Liang, T.; Douberly, G.E., “Observation of the Q(3/2) L-doublet transitions for X 2P3/2 OD in Helium Nanodroplets” Molecular Physics, (2014), 112, 301-303.

  10. Moradi, C.P.; Douberly, G.E.; “On the Stark effect in open shell complexes exhibiting partially quenched electronic angular momentum: Infrared laser Stark spectroscopy of OH-C2H2, OH-C2H4, and OH-H2O” Journal of Molecular Spectroscopy, (2015), 314, 54-62.

  11. Hernandez, F.J.; Brice, J.T.; Leavitt, C.M.; Liang, T.; Raston, P.L.; Pino, G.A.; Douberly, G.E. "Mid-Infrared Signatures of Hydroxyl Containing Water Clusters: Infrared Laser Stark Spectroscopy of OH-H2O and OH(D2O)n (n=1-3)" Journal of Chemical Physics, (2015), 143, 164304.

  12. Morrison, A.M.; Agarwal, J.; Schaefer, III H.F.; Douberly, G.E., “Infrared laser spectroscopy of the CH3OO radical formed from the reaction of CH3 and O2 within a helium nanodroplet” Journal of Physical Chemistry A, (2012), 116, 5299-5304.

  13. Raston, P.L.; Liang, T.; Douberly, G.E., “Infrared spectroscopy of HOOO and DOOO in 4He nanodroplets” Journal of Chemical Physics, (2012), 137, 184302.

  14. 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.

  15. Liang, T.; Magers, D.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.

  16. 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 Kelvin: Benchmark Thermochemistry of a Gas-Phase Peptide” Journal of Physical Chemistry A, (2014), 118, 9692-9700.

  17. 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-3-methylimidazolium bis(trifluoromethylsulfonyl)imide” Journal of Physical Chemistry A, (2013), 117, 9047-9056.

  18. 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.

  19. 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.

  20. Douberly, G.E.; Miller, R.E.; Xantheas, S.S. “Formation of Exotic Networks of Water Clusters in Helium Droplets Facilitated by the Presence of Neon Atoms” Journal of the American Chemical Society, (2017), 139, 4152-4156.

Helium Nanodroplet Isolation Methodology

Automation of an 'Aculight' Optical Parametric Oscillator

Joe on Machine