Mark A. Smith

Honors

• Visiting Fellow, Joint Institute for Laboratory Astrophysics, University of Colorado, 2002-2003
• Alexander von Humboldt Research Fellowship, Department of Physics, Technical University, Chemnitz, 2000
• CNRS Invited Visiting Professor, Department of Atomic and Molecular Physics, University of Rennes, 1997-1999
• Alexander von Humboldt Research Fellowship, Department of Physics, University of Freiburg, 1992
• American Society for Mass Spectroscopy Award for Young Academic Mass Spectrometrists, 1988

Education and Appointments

• B.S. 1976, University of Oregon
  
• M.S. 1978, Massachusetts Institute of Technology
  
• Ph.D. 1982, Joint Institute for Laboratory Astrophysics, University of Colorado
  

Research Interests

• Physical
  
• Catalysis and Reaction Dynamics
  
• Gas Phase Structure and Spectroscopy
  
• Instrumentation
  
• Materials Synthesis and Characterization
  
• Polymers
  

Research Summary

One area of our research program is centered about the study of molecular collision dynamics in the gas phase. A large part of the work, both experimental and theoretical, is associated with the development of new supersonic flow reactors for low temperature kinetic measurement. These techniques now allow the study of gas phase ion and free radical reactions from 300 K down to temperatures below 1 K. The results are providing critical insight into reaction mechanisms and find direct application to the study of chemical evolution in interstellar media and terrestrial and planetary atmospheres. Experimental studies have focused on the behavior of termolecular association processes and their relation to the lifetimes of bimolecular encounters, the dynamics of bimolecular light and heavy atom transfer reactions and electronic, vibrational and rotational energy transfer processes of small molecules and ions at low temperature.

In this area we are currently studying 10K reactions of quantum state selected HBr⁺(V,J,I) with HBr and H₂ to gain insight into competition between relocation, energy transfer and chemical reaction of internally excited species. We are also looking at the low temperature rates of reaction (50-250K) of NH radical and H and D atoms with variety of small molecules related to gas chemistry of planetary atmospheres and the ISM.

Aligned with our continuing interests in laser assisted chemistry we are studying reactions with demonstrated sensitivity to vibrational excitation. We have used this phenomenon to perform sensitive near single ion absorption spectroscopy in the infrared and are working to expand this to cover small molecular cations and anions for which vibrational spectroscopy is poorly understood. In this regard we are currently planning to build a 10K ion trap in our Tucson laboratory to continue this work. This radiofrequency ring electrode trap will allow the ability to study both ion spectroscopy as well as slow collisional processes, such as radiation association, not easily amenable to supersonic flow systems. The trap will be specifically designed to investigate ion reactions with unstable species such as atoms and small radicals.

A new direction for our group has involved the study of the organic chemistry of Saturn's large moon, Titan. Ion and photochemistry in the dense upper atomosphere of this object produces large quantities of organic aerosols, dubbed tholins. These tholins fall to the 100K surface and providing the organic feedstock for subsequent hydrolysis or oxidation chemistry. The development of this chemistry , its potential role in prebiological processes on Titan are of particular interest. The work in our group involves laboratory generation of tholin analogues and the determination of physical characteristics and chemical reactivity of this complex material. Short term goals are associated with providing interpretive insight into the Cassini-Huygens mission data coming back in early 2005 as well as to provide design input for a new Titan surface probe containing the instrumentation for a potential follow-on mission to probe directly the Titan surface chemistry. This work is in collaboration with scientists at the UA Planetary Science Department, Caltech and the Jet Propulsion Laboratory.

Selected Publications

• H. Imanaka and M.A. Smith, “EUV Photochemical Production of Unsaturated Hydrocarbons Initiated by Dissociative Charge Transfer Reaction of CH₄”, J. Phys. Chem. A, submitted.

• C.D. Niesh, J.I. Lunine, A. Somogyi, H. Imanaka, and M.A. Smith, “Rate Measurements of the Hydrolysis of Complex Organic Macromolecules in Cold Aqueous Solutions: Implications for Prebiotic Chemistry on the Early Earth and Titan”, Astrobiology 8, 273 (2008).

• A.E. Belikov and M.A. Smith, “Reactions of HBr⁺ Ions in the ²Π_i, v⁺ Quantum States with H₂ and HBr Molecules”, Russ. J. Phys. Chem. A 82, 789 (2008).

• H. Imanaka and M.A. Smith, “The Role of Photoionization in the Formation of Complex Organic Molecules in Titan’s Upper Atmosphere”, Geophys. Res. Lett. 34, L02204 (2007).

• D. Gerlich and M.A. Smith, “Laboratory Astrochemistry: Studying Molecules Under Inter- and Circumstellar Conditions”, Physica Scripta 73, C32 (2006).

• A.E. Belikov and M.A. Smith, “Branching and Rate Coefficients of the HBr⁺ + HBr Reaction Through the Isotope-Resolved REMPI Technique”, Int. J. Mass Spectrom. 246, 43 (2005).

• C. Mullen and M.A. Smith, “Temperature Dependence and Kinetic Isotope Effects for the OH + HBr Reaction and H/D Isotopic Variants at Low Temperatures (53 – 135 K) Measured Using a Pulsed Supersonic Laval Nozzle Flow Reactor”, J. Phys. Chem. A 109, 3893 (2005).

• C. Mullen and M.A. Smith, “Low Temperature NH (X ³Σ^-) Radical Reactions with NO, Saturated, and Unsaturated Hydrocarbons Studied in a Pulsed Supersonic Laval Nozzle Flow Reactor Between 53 and 188 K”, J. Phys. Chem. A 109, 1391 (2005).

• Somogyi, C-H. Oh, and M.A. Smith, “Organic Environments on Saturn’s Moon, Titan: Simulating Chemical Reactions and Analyzing Products by FT-ICR and Ion-Trap Mass Spectrometry”, J. Am. Soc. Mass Spectrom. 16, 850 (2005).

• R. Hodyss, G. McDonald, N. Sarker, M.A. Smith, P.M. Beauchamp, and J.L. Beauchamp, “Fluorescence Spectra of Titan Tholins: In-Situ Detection of Astrobiologically Interesting Areas on Titan’s Surface”, Icarus 171, 525 (2004).

• T. Spangenberg, S. Köhler, B. Hansmann, U. Wachsmuth, B. Abel, and M.A. Smith, “Low-Temperature Reactions of OH Radicals with Propene and Isoprene in Pulsed Laval Nozzle Expansions”, J. Phys. Chem. A 108, 7527 (2004).

• A.E. Belikov and M.A. Smith, “Low-Temperature Kinetics of the Charge- and Atom-Transfer Reaction (Br⁺, HBr⁺ [²Π_i, v⁺], DBr⁺ [²Π_i, v⁺]) + (HBr, DBr) → (HBr⁺, DBr⁺, H₂Br⁺, D₂Br⁺, HDBr⁺)”, J. Phys. Chem. A 108, 3447 (2004).

• A.E. Belikov and M.A. Smith, “State-Specific Low Temperature Reactions (HBr⁺, DBr⁺) [²Π_i, v] + (H₂, D₂): Channels and Rates”, Chem. Phys. Lett. 387, 7 (2004).

• N. Sarker, A. Somogyi, J. I. Lunine, and M.A. Smith, “Titan Aerosol Analogues: Analysis of the Nonvolatile Tholins”, Astrobiology 3, 719 (2003).

• M.A. Smith, S. Schlemmer, J. von Richthofen, and D. Gerlich, “HOC⁺ + H₂ Isomerization Rate at 25 K: Implications for the Observed [HCO⁺]/[HOC⁺] Ratios in the Interstellar Medium”, Astrophys. J. 578, 87-90 (2002).

• S. Schlemmer, E. Lescop, J. von Richthofen, D. Gerlich, and M.A. Smith, “Laser Induced Reactions in a 22-Pole Ion Trap: C₂H₂⁺ + hν₃ + H₂ → C₂H₃⁺ + H”, J. Chem. Phys. 117, 2068-2075 (2002).

• M.A. Smith, “Low Temperature Rate Studies of Ions and Radicals in Supersonic Flows”, in International Reviews in Physical Chemistry, T.S. Zwier and D.C. Clary, Eds., 17, 35 (1998).

• D.B. Atkinson and M.A. Smith, “Design and Characterization of Pulsed Uniform Supersonic Expansions for Chemical Applications”, Rev. Sci. Instrum. 66, 4434 (1995).

• M.A. Smith, “Ion-Molecule Reaction Dynamics at Very Low Temperatures”, in Unimolecular and Biomolecular Reaction Dynamics, Vol. 1, C.Y. Ng, T. Baer, and I. Powis, Eds., Wiley, New York, 183 (1994).