Collision Dynamics of Rare Gas Atoms and CO2 with Hydrocarbon Surfaces

  1. 1. Ne-Atom Collision Dynamics with Alkylthiolate Self-Assembled Monolayer and Squalane Surfaces.
  2. Energy-transfer dynamics associated with Ne atom collisions with a n-hexylthiolate self-assembled monolayer (SAM) surface were studied in chemical dynamics simulations by using both harmonic/separable and anharmonic/coupled surface models for the SAM.1

fig1
Chain orientation parameter of the anharmonic and harmonic SAM surfaces after collision with a Ne atom.

  1. Simulations were used to provide an atomic-level understanding of an experimental study of Ne + H-SAM collision dynamics.2

fig1
Final angular energy distributions as a function of incident energy/polar angle.

  1. A washboard with moment of inertia (WBMI) model of gas surface scattering was proposed and applied.3

fig1
Representation of the washboard with a moment of inertia (WBMI) model.

  1. A chemical dynamics simulation was performed to study collisions between Ne atoms and a liquid squalane surface.4

fig1
Probability of first impact on different carbon atom groups of the squalane moleque. Groups containing primary, second, and tertiary carbon atoms are distinguished by color bars: red for primary carbon atoms, green for secondary carbon atoms, and blue for tertiary carbon atoms. The overall percentages of different types of carbon atom groups are shown in thepie chart (right); groups containing primary carbon atoms are further divided into terminal and side groups, and their relative ratios are shown in the pie chart (left).

  1. 2. Intermolecular Potentials for Ar-Atom Scattering off SAM Surfaces.
  2. Simulating rare gas/surface collisions requires accurate intermolecular potentials between the rare gas atoms and surfaces. Intermolecular potentials, for Ar-atoms interacting with these surfaces, were modeled by CCSD(T) calculations for Ar-CF4 and Ar-CH3OH.5

fig1
Geometries of the Ar-CH3OH van der Waals complexes S1, S2, and S3 determined by MP2/aug-cc-pVTZ calculations.

  1. 3. Dynamics of CO2 Scattering off a Perfluorinated Self-Assembled Monolayer Surface.
  2. The dynamics of collisions of CO2 with a perfluorinated alkanethiol self-assembled monolayer (F-SAM) on gold were investigated by classical trajectory calculations.6

fig1
Structure of the CO2••CF4 van der Waals complex optimized at the MP2/cc-pVTZ level of theory.

  1. The above study was extended by using a united atom (UA) model for the CF3 and CF2 groups of the F-SAM.7

fig1
Two orientations between CO2 and CF4 used to calculate the UA model interaction potential between CO2 and F-SAM surface.

  1. 4. Chemical Dynamics Study of Intra-surface Hydrogen-Bonding Effects in Gas-Surface Energy Exchange and Accommodation.
  2. Chemical dynamics simulations were performed to compare the efficiency of energy transfer in collisions of Ar with H-SAM and OH-SAM alkyl thiol surfaces and compare with previous experiments.8

fig1
Representative snapshots of the structure of the Nc=11 HO-SAM surface at 300K shown with and without the underlying methylene chains and gold atoms.

References

  1. 1. "Role of Surface Intramolecular Dynamics in the Efficiency of Energy Transfer in Ne Atom Collisions with a n-Hexylthiolate Self-Assembled Monolayer." Journal of Physical Chemistry A 107, 10600-10607 (2003)
    T.-Y. Yan, N. Isa, K. D. Gibson, S. J. Sibener and W. L. Hase
  2. 2. "Experimental and Simulation Study of Neon Collision Dynamics with a 1-Decanethiol Monolayer." Journal of Chemical Physics 120, 2417-2433 (2004)
    N. Isa, K. D. Gibson, T.-Y. Yan, W. L. Hase and S. J. Sibener
  3. 3. "A Washboard with Moment of Inertia Model of Gas-Surface Scattering." Journal of Chemical Physics 120, 1031-1043 (2004)
    T.-Y. Yan, W. L. Hase and J. C. Tully
  4. 4. "Chemical Dynamics Simulation of Ne Atom Scattering off a Squalane Surface." Journal of Physical Chemistry C 112, 20340-20346 (2008)
    Y. Peng, L. Liu, Z. Cao, S. Li, O. A. Mazyar, W. L. Hase and T.-Y. Yan
  5. 5. "Ab Initio and Analytic Intermolecular Potentials for Ar-CH3OH." Physical Chemistry Chemical Physics 8, 4678-4684 (2006)
    U. S. Tasić, Y. Alexeev, G. Vayner, D. Crawford, T. L. Windus and W. L. Hase
  6. 6. "Chemical Dynamics Simulations of CO2 Scattering off a Fluorinated Self-Assembled Monolayer Surface." Journal of Physical Chemistry C 111, 354-364 (2007)
    E. Martínez-Núñez, A. Rahaman and W. L. Hase
  7. 7. "Dynamics of CO2 Scattering off a Perfluorinated Self-Assembled Monolayer. Influence of the Incident Collision Energy, Mass Effects, and Use of Different Surface Models." Journal of Physical Chemistry A 113, 3850-3865 (2009)
    J. J. Nogueira, S. A. Vázquez, O. A. Mazyar, W. L. Hase, B. G. Perkins, Jr., D. J. Nesbitt and E. Martínez-Núñez
  8. 8. "Chemical Dynamics Study of Intrasurface Hydrogen-Bonding Effects in Gas-Surface Energy Exchange and Accommodation." Journal of Physical Chemistry C 112, 476-490 (2008)
    U. S. Tasić, B. S. Day, T.-Y. Yan, J. R. Morris and W. L. Hase