Numerical Simulation And Verified Of Interaction Between Atomic Oxygen And Molybdenum Disulfide

The molecular dynamics calculation can reveal some physical and chemical processes that are neither to be observed by the on-ground experiments, nor to be simulated by the quantum chemical calculation. It helps to understand the interaction between particles and materials and its mechanism deeply as well. The present simulation of interaction between atomic oxygen（AO） and MoS₂ used a Reaxff-force-field potential based molecular dynamics method. The physical and chemical process, AO interacting with MoS₂, was described by the surface structure,radial distribution function（RDF） spectrum, amount of reacted AO, valence of Mo and S, and invasive depth of AO, which was given by the simulating calculations. The calculation also illustrated the effects of temperature, AO’s speed, and different lattice planes of MoS₂ reacting with AO. The calculation results were verified by the on-ground AO exposure experiments.The simulation shows that AO firstly preferentially absorbs on the location between bonding of S and chemically reacts with S atom. The formed sulfur oxide molecular is likely to leave the surface. Then, AO enters into substrate by diffusion reacting with S and/or Mo, resulting in formation of amorphous structure in the AO’s invasive area. Since the Mo and/or sulfur oxide molecular on surface prevent the subsequent AO entering into substrate, the invasive depth of AO is three molecular layers thick. Under AO exposure, Mo and S mainly show the valence of Mo6+, Mo4+,Mo2+, S6+, S4+, and S2+. During above process, only part of AOs react with MoS₂, while the rest of AOs rebounds to vacuum layer or forms O2 leaving the surface.When the temperature rises from 200 K to 350 K without changing AO speed and the AO speed rises from 3.9km/s to 7.8km/s without changing temperature, the increase of temperature and AO’s speed lead to augment of Mo6+ and/or S6+, and decrease of S2+.These factors enhances the degree of oxidation of MoS₂. At the same time, the number of reacting AO and the depth of AO invasion increase with the augment of temperature and AO’s speed. It also increase the area of amorphous region. Compared with Armchair,AO prefers to to react with Zigzag and diffuse, which leads to form a deeper invasive depth. The formed amorphous and the valance are in accordance with the on-ground AO exposure experiments which verified the correctness of simulation.