TY - JOUR
T1 - Chemical Dynamics Simulation of Low Energy N2 Collisions with Graphite
AU - Majumder, Moumita
AU - Bhandari, Hum N.
AU - Pratihar, Subha
AU - Hase, William L.
N1 - Funding Information:
The research reported here is based upon work supported by the Air Force Office of Scientific Research (AFOSR) Grant FA9550-16-1-0133 and the Robert A. Welch Foundation Grant D-0005. Support was also provided by the High Performance Computing Center (HPCC) at Texas Tech University, under the direction of Philip W. Smith. Some of the computations were also performed on the Chemdynm cluster of the Hase Research Group.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2018/1/11
Y1 - 2018/1/11
N2 - A chemical dynamics simulation was performed to study low energy collisions between N2 and a graphite surface. The simulations were performed as a function of collision energy (6.34 and 14.41 kcal/mol), incident polar angle (20-70°) and random azimuthal angle. The following properties were determined and analyzed for the N2 + graphite collisions: (1) translational and rotational energy distributions of the scattered N2; (2) distribution of the final polar angle for the scattered N2; (3) number of bounces of N2 on the surface before scattering. Direct scattering with only a single bounce is dominant for all incident angles. Scattering with multiple collisions with the surface becomes important for incident angles far from the surface normal. For trajectories that desorb, the parallel component of the N2 incident energy is conserved due to the extremely short residence times of N2 on the surface. For scattering with an incident energy of 6.34 kcal/mol, incident polar angle of 40°, and final polar angle of 50° the percentage incident energy loss is 29% from the simulations, while the value is 27% for a hard cube model used to interpret experiment (J. Phys.: Condes. Matter 2012, 24, 354001). The incident energy is primarily transferred to surface vibrational modes, with a very small fraction transferred to N2 rotation. An angular dependence is observed for the energy transfer, with energy transfer more efficient for incident angles close to surface normal.
AB - A chemical dynamics simulation was performed to study low energy collisions between N2 and a graphite surface. The simulations were performed as a function of collision energy (6.34 and 14.41 kcal/mol), incident polar angle (20-70°) and random azimuthal angle. The following properties were determined and analyzed for the N2 + graphite collisions: (1) translational and rotational energy distributions of the scattered N2; (2) distribution of the final polar angle for the scattered N2; (3) number of bounces of N2 on the surface before scattering. Direct scattering with only a single bounce is dominant for all incident angles. Scattering with multiple collisions with the surface becomes important for incident angles far from the surface normal. For trajectories that desorb, the parallel component of the N2 incident energy is conserved due to the extremely short residence times of N2 on the surface. For scattering with an incident energy of 6.34 kcal/mol, incident polar angle of 40°, and final polar angle of 50° the percentage incident energy loss is 29% from the simulations, while the value is 27% for a hard cube model used to interpret experiment (J. Phys.: Condes. Matter 2012, 24, 354001). The incident energy is primarily transferred to surface vibrational modes, with a very small fraction transferred to N2 rotation. An angular dependence is observed for the energy transfer, with energy transfer more efficient for incident angles close to surface normal.
UR - http://www.scopus.com/inward/record.url?scp=85040520278&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.7b10338
DO - 10.1021/acs.jpcc.7b10338
M3 - Article
AN - SCOPUS:85040520278
VL - 122
SP - 612
EP - 623
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 1
ER -