Reactive and Inelastic Scattering Dynamics of Hyperthermal O and O2 from a Carbon Fiber Network Journal Article uri icon

Overview

abstract

  • ; The; reactive and inelastic scattering dynamics of; ground-state atomic and molecular oxygen from a carbon fiber network at 1023-1823 K was; investigated with a molecular beam-surface scattering technique. A molecular beam containing hyperthermal O and O; 2; with a mole ratio of 0.92:0.08 and nominal velocity of 8 km s; -1; was; directed at the network, and time-of-flight distributions of the scattered; products were collected at various angles with the use of a rotatable mass; spectrometer detector. O atoms exhibited both impulsive scattering (IS); and thermal desorption (TD) dynamics, where the TD O-atom flux; increased with surface temperature and the IS O-atom flux remained relatively constant. While the; majority of the TD O atoms desorbed promptly after the beam pulse struck the; network, signatures of thermal processes occurring over long residence times; were also observed. Evidence of O; 2; reactions was not observed, and; the behavior of the inelastically scattered O; 2; was invariant to the; temperature of the network and showed both IS and TD dynamics. The dominant reactive product was CO, whereas CO; 2; was a minor product. Both these products showed only TD dynamics. The observed; flux of CO initially increased with temperature and then reached a plateau; above which the flux no longer increased with temperature, over the temperature; range studied. Thermally desorbed CO products exited the network promptly or; after relatively long residence times, and two populations of CO with long; residence times were distinguished. Hysteresis was observed in the; temperature-dependent flux of thermally desorbed O and CO, with opposing trends; for the two products. This work follows similar studies in our; laboratory where the target materials were vitreous carbon and highly oriented; pyrolytic graphite. The data suggest that the chemical reactivity of the three; forms of; sp; 2; carbon surfaces; is similar and that the differences arise from the variations of the; morphology.;

publication date

  • March 23, 2021

has restriction

  • hybrid

Date in CU Experts

  • November 23, 2021 4:16 AM

Full Author List

  • Poovathingal S; Qian M; Murray V; Minton T

author count

  • 4

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