Chemical Dynamics Simulations of High Energy Xenon Atom Collisions with the {0001} Surface of Hexagonal Ice

• Published in: Journal of physical chemistry. C Vol. 117; no. 5; pp. 2183 - 2193
• Main Authors: Pratihar, S, Kohale, S. C, Yang, L, Manikandan, P, Gibson, K. D, Killelea, D. R, Yuan, H, Sibener, S. J, Hase, W. L
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 07.02.2013
• Subjects: Atomic, molecular, and ion beam impact and interactions with surfaces; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Impact phenomena (including electron spectra and sputtering); Physics; Atomic beams; Thermalization; Xenon; Desorption; Ice; Penetration depth; Trapping; Surface scattering; Particle-surface interactions; Incidence angle; Ab initio calculations; Dynamic model; Subsurface
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp3112028

Simulation results are presented for Xe atoms colliding with the {0001} surface of hexagonal ice (I h) with incident energies E I of 3.88, 4.56, 5.71, and 6.50 eV and incident angles θI of 0, 25, 45, and 65°. The TIP4P model was used for ice and ab initio calculations were performed to determine an accurate Xe/ice potential. Three types of events were observed; that is penetration below the ice surface and then desorption, penetration with Xe remaining in ice for times greater than 6 ps trajectory, and direct scattering without surface penetration. Surface penetration is most probable for normal (θI = 0°) collisions and direct scattering becomes important for θI = 45° and 65°. Penetration into ice becomes deeper as E I is increased. For θI = 0 and 25°, all of the Xe atoms penetrate the surface and there is no direct scattering. The probability that the Xe atoms remain trapped below the surface increases as E I is increased and is more than 70% for θI = 0° and E I = 6.50 eV. For θI of 0 and 25° the trapped Xe atoms have a thermal energy of ∼25 meV at 6 ps and are close to being thermalized. For θI of 0 and 25° the average translational energy of the scattered Xe-atoms ⟨E F⟩ is highest when θF is very close to normal and then gradually decreases for higher values of θF. For θI of 45 and 65°, ⟨E F⟩ is less than 250 meV for θF varying from 0 to 40°, but for larger θF the value of ⟨E F⟩ rapidly increases to ∼1/3 to 1/2 of the collision energy. The probability of the subsurface Xe desorbing is greatest between 0 and 3 ps, with as much as 65% of the desorption occurring within a 1 ps interval of this time frame. Desorption is greatly diminished at longer times consistent with Xe becoming more thermalized. Simulation results using the TIP3P model for ice are similar to those above for the TIP4P model, with the caveat that trapping below the ice surface is more pronounced for the TIP3P model. The simulation results are in overall quite good agreement with experiment.