The interaction of plasmas with surfaces can lead to different surface processes active in different collisional energy regimes according to the behaviour of the gas-phase species and substrate involved. In particular, atom recombination at surfaces can be an effective source of roto-vibrationally excited molecules and, at the same time, an effective process for surface atom abstraction and atom removal from the plasma region [1]. Such processes have a strong impact on the physical-chemistry of the bulk region and at the plasma-surface interface. In fact, it is well established that the reactivity of molecular plasmas under low-pressure, lowtemperature conditions depends on, and is often controlled by, the formation of energetically vibrationally activated molecules [2]. Therefore, it is important to understand the processes by which one can store vibrational quanta in the vibrational manifold of the active molecules in the plasma or gaseous media. This contribution is focused on the molecular surface processes due to the interaction of a flux of H and O atoms colliding with a silica surface at low-collisional energies (0.1-3 eV). Hydrogen and oxygen plasmas are currently of great interest in different research areas of fundamental and technological interest such as microelectronics, nano-medicine, modern solar cells, fusion reactors, astrophysics and aerothermodynamics. We will present the results obtained during the last years by our group in the study of the interaction of atoms of H and O on a silica surface based on analytical DFT Potential Energy Surfaces [3, 4]. Molecular Dynamics calculations have been performed using a semiclassical collisional method that provides a detailed knowledge of the multiphonon inelastic processes that assist the dynamics of the chemical and physical phenomena due to the chemi-/physic-sorption of atoms and molecules on substrate [5]. In particular, results concerning the recombination of H [4] and O [6] atoms on the silica surface will be discussed, in a comparative manner, respect to the recombination probabilities and coefficients, energy distribution in the final states and vibrational distributions of the formed molecules. [1] M. Cacciatore and M. Rutigliano, 2009 Plasma Sources Sci.Technol. 18 023002 [2] J. Amorim , J. Loureiro and D. Schram , 2001 Chem. Phys. Lett., 346 443-8 [3] M. Rutigliano ,C. Zazza , N. Sanna , A. Pieretti , G.Mancini , V. Barone and M. Cacciatore, 2009 J. Phys. Chem. A 113 15366-75 [4] M. Rutigliano, P. Gamallo, R. Sayós, S. Orlandini and M. Cacciatore, Plasma Sources Sci. Technol. 2014 23 045016 [5] G. D. Billing, Dynamics of Molecule Surface Interactions; Wiley: New York, 2000 [6] M. Rutigliano and M. Cacciatore, J. Therm. Heat Transfer 2015 in press doi: http://arc.aiaa.org/doi/abs/10.2514/1.T4596
Molecular Dynamics simulations of hydrogen and oxygen atom on silica surface
M Rutigliano;
2015
Abstract
The interaction of plasmas with surfaces can lead to different surface processes active in different collisional energy regimes according to the behaviour of the gas-phase species and substrate involved. In particular, atom recombination at surfaces can be an effective source of roto-vibrationally excited molecules and, at the same time, an effective process for surface atom abstraction and atom removal from the plasma region [1]. Such processes have a strong impact on the physical-chemistry of the bulk region and at the plasma-surface interface. In fact, it is well established that the reactivity of molecular plasmas under low-pressure, lowtemperature conditions depends on, and is often controlled by, the formation of energetically vibrationally activated molecules [2]. Therefore, it is important to understand the processes by which one can store vibrational quanta in the vibrational manifold of the active molecules in the plasma or gaseous media. This contribution is focused on the molecular surface processes due to the interaction of a flux of H and O atoms colliding with a silica surface at low-collisional energies (0.1-3 eV). Hydrogen and oxygen plasmas are currently of great interest in different research areas of fundamental and technological interest such as microelectronics, nano-medicine, modern solar cells, fusion reactors, astrophysics and aerothermodynamics. We will present the results obtained during the last years by our group in the study of the interaction of atoms of H and O on a silica surface based on analytical DFT Potential Energy Surfaces [3, 4]. Molecular Dynamics calculations have been performed using a semiclassical collisional method that provides a detailed knowledge of the multiphonon inelastic processes that assist the dynamics of the chemical and physical phenomena due to the chemi-/physic-sorption of atoms and molecules on substrate [5]. In particular, results concerning the recombination of H [4] and O [6] atoms on the silica surface will be discussed, in a comparative manner, respect to the recombination probabilities and coefficients, energy distribution in the final states and vibrational distributions of the formed molecules. [1] M. Cacciatore and M. Rutigliano, 2009 Plasma Sources Sci.Technol. 18 023002 [2] J. Amorim , J. Loureiro and D. Schram , 2001 Chem. Phys. Lett., 346 443-8 [3] M. Rutigliano ,C. Zazza , N. Sanna , A. Pieretti , G.Mancini , V. Barone and M. Cacciatore, 2009 J. Phys. Chem. A 113 15366-75 [4] M. Rutigliano, P. Gamallo, R. Sayós, S. Orlandini and M. Cacciatore, Plasma Sources Sci. Technol. 2014 23 045016 [5] G. D. Billing, Dynamics of Molecule Surface Interactions; Wiley: New York, 2000 [6] M. Rutigliano and M. Cacciatore, J. Therm. Heat Transfer 2015 in press doi: http://arc.aiaa.org/doi/abs/10.2514/1.T4596I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.